I love my HHR but would like to increase the MPG.
My thoughts are
1. lowering car about an inch. That reduces the undercar turbulence and overall drag coeficient. Maybe 1 MPG or more at all speeds? Has anyone verified MPG improvements from lowering? Looks good to.
2. Complete exhaust and K& N intake filter. Some of the exhaust systems now days are like a potatoe in the pipe to make them meet emmisions and make them quiet. Maybe 1 to 2 MPG?
3. Tune, now in another thread here there are some claims of 5 MPG and I think that may be optimistic but if there is a verifiable real world improvement of 2 MPG then that would be significant.

Note items 2 and 3 would increase performance and mileage only IF you keep your foot out of it.

So if the above items could get an honest 4 or 5 MPG improvement then I think that would be worth it.

There are some things that I consider stupid such as drafting big rigs or going under posted speed limit that will save gas. Do those things please sign your organ donor cards.

I already try to keep my tires inflated up and try to keep my foot out of it but I do cruise at a safe speed and do not hold up traffic or create a hazard.

Also has anyone any definative proof of mileage increases with air conditioning off? Here in Texas it is 80* to 113* on the DIC about 9 months of the year so air conditioning off is not going to happen.

Look forward to your opinions. Curly

How many years does it take to break even in gas savings from those mods? 10-15?

There is no magic to better gas mileage. The best thing to do is drive smart. And, it's FREE.

I know what you're feeling though. The MPG display on the DIC is a curse. I never worried about it when I couldn't see it. I have to try to just keep it on outside temp and RELAX while I drive, like it should be, and not worry about picking up .2 mpg on this leg.

Unless you're also replacing the catalytic converter (illegal to do so before 50,000 miles) with a low restriction one (Random tech, etc), a catback exhaust is a waste, in my opinion but others may disagree.

A K&N will do nothing for your mpg. If it doesn't coat your MAF sensor wires with oil as recieved when you buy it, it will one day after you finally clean and re-oil it. I'm anti 'oiled gauze' air filters, but that's just me... I just don't like oily cotton in my intake air path.

General Motors has tuned these cars for the best fuel efficiency and emissions performance, why wouldn't they? They want to be able to advertise the best MPG numbers possible, it helps sell cars. Trying to out-think the GM Powertrain engineers on emissions and fuel efficiency is a waste of time-- they know what they're doing.

I changed my Exhaust to a GMPP Cat back exhaust and changed my oil on the same day and used full synthetic and ever since my mpgs went up about 2-3 mpg in city and highway.

A restrictive exhaust absolutly will hurt performance and mileage. The question is how much and is it worth the expense? Factory exhaust are quiet (restrictive) because most people want them quiet.
The factory has to make some sacrifices in performance and mileage to get it quiet and to meet all emmisions etc.

A restrictive exhaust absolutly will hurt performance and mileage. The question is how much and is it worth the expense? Factory exhaust are quiet (restrictive) because most people want them quiet.
The factory has to make some sacrifices in performance and mileage to get it quiet and to meet all emmisions etc.

Actually sound levels are dictated by the Federal Government. So exhaust levels, as well as the intake levels (ala the big black plastic box under the hood), are "muted" to comply with the requirement. Aftermarket sales is a different scenario.

I think Lone Ranger's comments sum the matter up quite nicely. But here in the land of the free and the home of the brave, you can do whatever you please to your own property.

I haven't found anyone yet that can comfortably tune HHRs that aren't SS models, but when I do i'll be happy to be their mule. I had great luck with tuning my z28, fuel mileage AND performance both went up significantly with a simple tune.

As for right now, I'm pretty satisfied with my mileage. I got 35 mpg on a trip from NJ to MD, most of the time doing 70 mph, AC on half the time. the DIC only said 32.5 and i was happy with that, but doing it the pen and paper way it was over 35. I realized then that my tires were only inflated to 28 psi (must have been from the dealer, haven't checked since I bought it) and I filled them up, waiting to see what the next tank will bring.

I love my HHR but would like to increase the MPG.
My thoughts are
1. lowering car about an inch. That reduces the undercar turbulence and overall drag coeficient. Maybe 1 MPG or more at all speeds? Has anyone verified MPG improvements from lowering? Looks good to.
2. Complete exhaust and K& N intake filter. Some of the exhaust systems now days are like a potatoe in the pipe to make them meet emmisions and make them quiet. Maybe 1 to 2 MPG?
3. Tune, now in another thread here there are some claims of 5 MPG and I think that may be optimistic but if there is a verifiable real world improvement of 2 MPG then that would be significant.

Note items 2 and 3 would increase performance and mileage only IF you keep your foot out of it.

So if the above items could get an honest 4 or 5 MPG improvement then I think that would be worth it.

There are some things that I consider stupid such as drafting big rigs or going under posted speed limit that will save gas. Do those things please sign your organ donor cards.

I already try to keep my tires inflated up and try to keep my foot out of it but I do cruise at a safe speed and do not hold up traffic or create a hazard.

Also has anyone any definative proof of mileage increases with air conditioning off? Here in Texas it is 80* to 113* on the DIC about 9 months of the year so air conditioning off is not going to happen.

Look forward to your opinions. Curly

Hey curly,
What engine
What trans
What is your best mileage over one tank
Wha is your avg mpg usually
What is the terrain like down there
What is your average trip distance.
What do you consider "good" mileage???
What is the normal highway speed that you drive?
What is the highway speed limit down there?

I'm that dude who annoyes people by putting 87 octane into a loaded SS while getting 36 mpg overall 66%hwy/33%cty
Later :)

Most car companies tune their cars based mostly on emmissions. But obviously MPG is taken into consideration when they set up the fuel mapping. Most of the tunes I have run into with other car manufacturers are set up a bit rich or "safe". Keeps them from having to replace as many parts under warranty.
I'm new to the HHR but if there is a piggyback tuner out there that can interface with a laptop that allows you to adjust A/F ratio I would be interested in it.

Hey curly?
You out there?

My HHR is auto with the 2.2 and my mileage is average 23 in the city daily driving and about 30 on the highway @ 80MPH. The car will get 38 MPG @ 55 to 60 MPH.
Overall I am pleased with the performance and mileage but I know that opening up the intake and exhaust should help it even more.

To anyone who can get 36 MPG average with a stock HHR that is great! But what if you could make some improvements and get 41 MPG?

Certainly there are things as a driver that can do to help the gas mileage but there are mechanical things we can do to improve it even more.

The intake and exhaust on factory cars is very restrictive to make the cars quiet and meet all regulations. There is a very good reason all of the race cars do not have mufflers and have big intakes.

If you can open up the exhaust and intake and get the fuel mixture right then your performance AND mileage will improve (if you keep your foot out of it)

My question is how much and what is the most cost effective things to do.

My HHR is auto with the 2.2 and my mileage is average 23 in the city daily driving and about 30 on the highway @ 80MPH. The car will get 38 MPG @ 55 to 60 MPH.
Overall I am pleased with the performance and mileage but I know that opening up the intake and exhaust should help it even more.

To anyone who can get 36 MPG average with a stock HHR that is great! But what if you could make some improvements and get 41 MPG?

Certainly there are things as a driver that can do to help the gas mileage but there are mechanical things we can do to improve it even more.

The intake and exhaust on factory cars is very restrictive to make the cars quiet and meet all regulations. There is a very good reason all of the race cars do not have mufflers and have big intakes.

If you can open up the exhaust and intake and get the fuel mixture right then your performance AND mileage will improve (if you keep your foot out of it)

My question is how much and what is the most cost effective things to do.

I'm all for 41 mpg, but that is a big jump. A couple of manufactures have exhausts and intakes for HHR's, (all engines i think). Ask someone with both upgrades their opinion.
Easy on the gas and easy on the brake in the city my friend, you'll get 5 mpg easy that way. No $300 intakes or $700 exhausts required. Im sure that the looks and sound has it's own dollar value that I can't put a number on :)

......................

The intake and exhaust on factory cars is very restrictive to make the cars quiet and meet all regulations. .............


Oh, so very FALSE statement!! :roll: :confused:

Oh, so very FALSE statement!! :roll: :confused:

I was being nice considering that he compared me to a "grandma" drivin 43 in the centerlane in the cobalt forum...lol All because I hypermile. Why is it always buy this buy that, bolt on this bolt on that to solve everything. What about upgrading/bolting-on somewhere between the steering wheel and the drivers seat?? I drive minimum the posted limit in the city, and much faster downhill...lol And I easily muster 28-29. No hypermile tricks. Just attentive driving. Add a bag of tricks and you get 33-35mpg. If you have mastered that....then throw some money at mods?

"I'm all for 41 mpg, but that is a big jump. A couple of manufactures have exhausts and intakes for HHR's, (all engines i think). Ask someone with both upgrades their opinion.
Easy on the gas and easy on the brake in the city my friend, you'll get 5 mpg easy that way. No $300 intakes or $700 exhausts required. Im sure that the looks and sound has it's own dollar value that I can't put a number on :)"

That is the whole thread here is I am asking those with the upgrades their opinions.
I definatly agree there is 5 MPG and more from driving technique but there is also some from mechanical improvements. That is what I am asking, not how to drive. I want my car to get the best MPG it can, What is the problem with that?

"I'm all for 41 mpg, but that is a big jump. A couple of manufactures have exhausts and intakes for HHR's, (all engines i think). Ask someone with both upgrades their opinion.
Easy on the gas and easy on the brake in the city my friend, you'll get 5 mpg easy that way. No $300 intakes or $700 exhausts required. Im sure that the looks and sound has it's own dollar value that I can't put a number on :)"

That is the whole thread here is I am asking those with the upgrades their opinions.
I definatly agree there is 5 MPG and more from driving technique but there is also some from mechanical improvements. That is what I am asking, not how to drive. I want my car to get the best MPG it can, What is the problem with that?

Nothin at all is wrong. Please...anyone...help curly out here and post your experience with intake and/or exhausts.

My only problem is that you did sorta make fun of me (albiet in the cobalt forum) and I wanted to make sure you understood hypermiling is probably the best mileage "upgrade" you can add to your car. I don't know of any mileage upgrade that wil pay itself back (gas saved vs upgrade cost) in less than 2 years. Let's say you get 25mpg overall and 17,500 miles a year. 700 gallons of gas will cost you $2800. If an upgrade will net 1-2mpg (lets say 1.5mpg) for $300, it will pay itself off after 2 years. By year 5 you will have saved $500, thats $8.33 a month for 60 months? That is IF..and this is the biggie IF it works.

So my feeling on these types of upgrades isn't so much they are not worth...it's just that you better get an apperance upgrade (cool looking color matched aluminum tube, or shiny stainless pipes with a throaty sound) in addition to your $8.33 a month savings.

You can do the math on hypermiling from 25mpg up to 30mpg, $467 saved in the first year, $2335 after...almost $40 a month saved. I managed to make 36 overall for an entire tank driving my normal routes and no extended highway (37mph and 11.6 mile trips) no cruise and 87 octane. I'm not saying that you should get that extreme with it....but it is possible.

I am not making fun of you or anyone on any forum. I just want better mileage from my car and not satifiied to say the car is perfect so work on my driving skills. My question is how to improve the car, driver is a whole different deal. And I am not worried abut how long it takes to get my money back on this. I bought this car, paid cash for it in full and really like it and will keep it for many years. I know saving weight will help but I am not pulling out the interior or anything sillly like that. I know there are mileage improvements from driver AND vehicle and vehicle is the question today.
What ever I do to this will pay for itself many times over long before I get rid of it. The car (truck, crossover, whatever) will get better performance, mileage, sound better and be more fun to drive. I think that is more than reason enough.

There are things I learned from my many years of dragracing cars. Some little things like just putting the factory front spoiler on and lowering car a few inches picks up several miles per hour in the 1/4 mile. That means it takes LESS horsepower to move the car.
When I first started racing it I had factory style exhaust. Then I went to a full 3 inch system and it went much faster. Then I removed exhaust and it picked up much more. I eventually ended up with the best comprimize for me with a huge 4 inch muffler system that was very short and did not even go back to axles. That allowed very good performance and cut down the noise (some!)
The right performance mods will help mileage and performance providing you do not put your foot in it and more power will be there if you need it.
I know lowering it will help the mileage some, it may be too small to notice or be worth anything but if it takes less horespower to move the vehicle at speed it takes less gas to.

I've noticed some decrease in mpg lately. I'm thinking that just about all the gas I can purchase has 10% or less ethanol content. I know ethanol produces less energy per gallon. Has anyone done any study on the effect of the 10% blend vs 100% gas? I use to routinely get 30+ mpg, but it seems that now I'm in the 27 mpg range. (10% lower mpg)

I am not making fun of you or anyone on any forum. I just want better mileage from my car and not satifiied to say the car is perfect so work on my driving skills. My question is how to improve the car, driver is a whole different deal. And I am not worried abut how long it takes to get my money back on this. I bought this car, paid cash for it in full and really like it and will keep it for many years. I know saving weight will help but I am not pulling out the interior or anything sillly like that. I know there are mileage improvements from driver AND vehicle and vehicle is the question today.
What ever I do to this will pay for itself many times over long before I get rid of it. The car (truck, crossover, whatever) will get better performance, mileage, sound better and be more fun to drive. I think that is more than reason enough.

There are things I learned from my many years of dragracing cars. Some little things like just putting the factory front spoiler on and lowering car a few inches picks up several miles per hour in the 1/4 mile. That means it takes LESS horsepower to move the car.
When I first started racing it I had factory style exhaust. Then I went to a full 3 inch system and it went much faster. Then I removed exhaust and it picked up much more. I eventually ended up with the best comprimize for me with a huge 4 inch muffler system that was very short and did not even go back to axles. That allowed very good performance and cut down the noise (some!)
The right performance mods will help mileage and performance providing you do not put your foot in it and more power will be there if you need it.
I know lowering it will help the mileage some, it may be too small to notice or be worth anything but if it takes less horespower to move the vehicle at speed it takes less gas to.

Well others here will be able to help you :) I'd try reposting this question rebadged as a "top speed/moe power/drag racing" thread, an you might get an answer if no one has pm'd you yet. Hypermiling is NO WAY to get alot of reponses.

I've noticed some decrease in mpg lately. I'm thinking that just about all the gas I can purchase has 10% or less ethanol content. I know ethanol produces less energy per gallon. Has anyone done any study on the effect of the 10% blend vs 100% gas? I use to routinely get 30+ mpg, but it seems that now I'm in the 27 mpg range. (10% lower mpg)

Check your average speed over a tank, compared the high and low mpg tanks. Also the number of cold starts hurts mileage also. Parking garages, super steep hills, parking lots, fast food restaurants etc. They also eat mileage right under your nose. I'm sure that you have already though about these things, but don't underestimate how much they can matter even in small doses.

Also the route you routinely drive has an effect. Stop and go traffic on a short route gets you less mpg vs less traffic and traffic lights on a longer route. The added mpg more than offsets the additional distance.

I also was kinda wondering if there was anything out there to increase mpg mechanically/electronically - best bang for the buck...

Also the route you routinely drive has an effect. Stop and go traffic on a short route gets you less mpg vs less traffic and traffic lights on a longer route. The added mpg more than offsets the additional distance.

I also was kinda wondering if there was anything out there to increase mpg mechanically/electronically - best bang for the buck...

Probably a tune. No shoe fits better than a cutom one made for YOU. Most other items have a lot of "buck" and not so much "bang".

This lower part is for anyone willing to read, not specifically GCarp

Please don't take this as a bash, burn, or flame..lol

If no one here wants to tune their driving (the 99% consensus from all people i converste with about mileage) then get a hybrid. It will go off electric in the city and below certain speeds, shift FOR you, and will do all the things I do with my clutch and ignition without having to pay attention. You'll get better mileage at whatever speed you choose to drive. It IS POSSIBLE to hypermile doin 80 on an interstate.

Once again dont thake this as a bash Im just making a analogy.

I am reminded of athletes who choose not to do the work (OR ENOUGH) but want the results. They buy drugs, inject , and cheat. I prefer the Jerry Rice or Jack Lalane style of bolt on :).

Performance and mileage go together in many ways.
Save weight your car will go faster and or get better mileage. Fact. That does not mean I am going to rip out all of the interior of my car to get better mileage. Lower weight= faster acceleration and better mileage because it takes less energy (gas) to accellerate the vehicle.
Better aerodynamics will increase performance and gas mileage. Fact. I am going to lower the vehicle about 2 inches all the way around but that is all I am not going to remove mirrors, antenae etc. Aerodynamics may not mean much at 10 MPH but at 60 or more it is huge. If you think it is not stick you hand out the window and see how much drag it has. Then think about how much air the whole car is pushing. Air drag takes horsepower (gas) to pusg vehicle. The faster you go the larger the difference it makes. Fact.
Increase the effeciency of the vehicle it will get better performance and mileage. Fact. I think right now I am going to put a K & N intake filter and axle back exhuast with a Trifecta tune. I have a friend who says he got 7 MPG better mileage with an Ariad (sp?) filter. He said he has an 11 gallon tank (Pontiac Grand Am?) and he gets over 100 miles more per tank. I am not expecting that much for an air filter but regardless it makes a noticeable difference. I am not going to remove the air conditioner or anything like that. Ideally you want to make the motor and car as effecient as possible with out giving up the creature comforts or safety features. I know for a fact you can increase performance and mileage with better intake and exhaust and tuned for it. I do not know exactly how much it will help and that is really what I am asking here, how much and which is best? Now if you make the mods and then run around wide open all the time then not only will your gas mileage stink you may get a bunch of tickets. The wrong mods will hurt your mileage and lighten your wallet. The right ones will help performance and save you money in the long run in gas savings. I plan on keeping my car for many years so these mods will pay off big time in performance, mileage and fun. Besides this is my baby and I want to improve it some, I already ordered some Solstice wheels, the lowering kit and deciding which other mods to make. I am also going to make some 100 mile trips at the same speed under as close as possible same conditions to verifiy the results. Hoping someone else had already done much of that and knows which ones work best.
Driving is also a big part of economy but certainly not the only thing and not what I am asking about here. There are several good threads on driving techniques but not much real world figures on the best mechanical improvements.
Ethanol will hurt mileage some. In my race car when I was using gas it took about 1 gallon of gas per pass, with Alcohol it takes about 2.5 gallons per pass. The car is MUCH faster on Alcohol though. Alcohol - does run cooler and has higher octane but it requires MUCH more fuel. Even a Ethanol 10% mixture decreases mileage some so in my opinion unless it was about 25% cheaper Ethanol does not make much sense to me in a daily driver.

Try it and see. Post your experiment technique and results here. Actually make a new thread, call it "Mods for Mileage" or something like that. There is a tune in my future so I will have many things to add.

"If no one here wants to tune their driving (the 99% consensus from all people i converste with about mileage) then get a hybrid. It will go off electric in the city and below certain speeds, shift FOR you, and will do all the things I do with my clutch and ignition without having to pay attention. You'll get better mileage at whatever speed you choose to drive. It IS POSSIBLE to hypermile doin 80 on an interstate."

Nobody said they do not want to tune their driving here. This whole thread is about Mechanical improvements or "Mods for Mileage" what ever you want to call it. Driving technique has been discussed on this forum before, I just want some good, knowledgeable opinions on the mechanical end of it.

You are apperiently very good at squeezing every last drop out of your car as a driver. That is good, you said in one of your posts that you turn the air conditioning off and crack the windows. Why do you do that? (for the same reason I want to make mechanical mods) Because it frees up some horsepower and saves some gas. The car does not have to work as hard to move the vehicle. You said a tune is in your future, are you doing it for the same reasons as I? to gain mileage? I would like to know how much a tune helps your car.

Nobody is dissagreeing the driver is important if your goal is gas mileage but the car is to and there are things you can do to improve it.

Turning the air conditioner off will help as will a tune, an intake filter, aero dynamic mods, exhaust system and yes driver to.

For my car I ordered a set of Solstice wheels, lowering kit, K & N filter, CGS axle back muffler system and going to do a Trifecta tune on it. Solstice wheels will not help mileage any but I like the way they look. I like the car and I will like it even more when the mods are done if they work as I think they will.

I am making some 100 mile test runs as a baseline and recording weather etc to get the most reliable results possible. Then I will do the lowering and test it again. I will know in a month or so how much the mods for mileage help and will post them here.
I do not want to make a job out of it I just want get better mileage and then enjoy the car. Curly

"If no one here wants to tune their driving (the 99% consensus from all people i converste with about mileage) then get a hybrid. It will go off electric in the city and below certain speeds, shift FOR you, and will do all the things I do with my clutch and ignition without having to pay attention. You'll get better mileage at whatever speed you choose to drive. It IS POSSIBLE to hypermile doin 80 on an interstate."

Nobody said they do not want to tune their driving here. This whole thread is about Mechanical improvements or "Mods for Mileage" what ever you want to call it. Driving technique has been discussed on this forum before, I just want some good, knowledgeable opinions on the mechanical end of it.

You are apperiently very good at squeezing every last drop out of your car as a driver. That is good, you said in one of your posts that you turn the air conditioning off and crack the windows. Why do you do that? (for the same reason I want to make mechanical mods) Because it frees up some horsepower and saves some gas. The car does not have to work as hard to move the vehicle. You said a tune is in your future, are you doing it for the same reasons as I? to gain mileage? I would like to know how much a tune helps your car.

Nobody is dissagreeing the driver is important if your goal is gas mileage but the car is to and there are things you can do to improve it.

Turning the air conditioner off will help as will a tune, an intake filter, aero dynamic mods, exhaust system and yes driver to.

For my car I ordered a set of Solstice wheels, lowering kit, K & N filter, CGS axle back muffler system and going to do a Trifecta tune on it. Solstice wheels will not help mileage any but I like the way they look. I like the car and I will like it even more when the mods are done if they work as I think they will.

I am making some 100 mile test runs as a baseline and recording weather etc to get the most reliable results possible. Then I will do the lowering and test it again. I will know in a month or so how much the mods for mileage help and will post them here.
I do not want to make a job out of it I just want get better mileage and then enjoy the car. Curly


Sounds good. Post with the same detail as my post. Plenty of silent views are interested. And loud mouths like me are really interested. I have not done a acceptable job testing air conditioning vrs windows cracked. I work in (50% of the time) in a harsh industiral environment. It always 90% humidity and always 10-15 degress above ambient in the COOL areas. So I work in the amazon weather 5 months out of th year. 90 degrees and windows down feels cool to me. I only run the a/c when my sons is riding with me. If it wasn't for that , I wouldnt have any use for A/c. It just dosent get that hot TO ME. Try the mods. let us know. If you can get me to 40 mpg, you will be the MAN.

From what I can tell it is going to be very difficult to get exact mileage improvements. The test run was mostly uphill on the way out and down hill on the way back. Mileage was about 3 MPG better on the return trip. On my test runs today I made a bunch of 10 or more mile tests at different speeds from 55 to 85 MPH. Atleast 2 test runs at each speed more than 10 miles each direction.
39.75 MPG average @55 MPH
37.1 MPG average @ 60
35.7 MPG average @ 65
31.1 MPG average @ 70
29.9 MPH average @ 75
29.1 MPG average @ 80
26.3 MPG average @85 MPH
Temperature was 90* and the alitimeter was at 450 feet above sea level with very little if any wind today. All the way I set it on cruize control and treid to keep it as consistant as possible to get accurate figures. Of course there are driving things I could do to improve that some but I am trying to get good numbers for before and after of my car.
My average city MPH is 22-24.

Several of my numbers really did not seem as consitant as I think they should have been and everal times I had someone pull in front of me where I had to slam brakes and then accelerate back up to speed so I know that may have hurt some.

I did a very short 60 MPH run with the air conditioner off and it was like being in an oven but the mileage went up from 37 average at that speed to 44 average. That seems much more than I expected so I will try to do that test again to verify. Has anyone done any mileage tests with and with out air conditioning??
I hope to do all of these again next week to get a better baseline prior to making the mods.
I am going to try to do the tests with the lowering only first as I want to know if that makes any difference, I know it should at speed but no idea how much.
I am hoping (expecting) 5 MPG gains on the highway at most all speeds and maybe 3 MPG in the city. I would not be suprized to see a few more MPG than that. Regardless everyone will know in about 4 to 6 weeks when all of the tests and mods are done.

I put about 240 miles on the car today doing the testing. The altitude climbs from 437 feet to about 1250 feet above sea level over the 120 miles before I turned around to make the return trip. Also started out with about 3/4 tank and there was less gas in the tank on the return trip so that lightens the car up some. Those two things probably accounted for about 3 MPG better mileage on the return trip at most speeds.
I will try to do all of my testing on this very same test road under as close as possible weather conditions. Each variable does make it difficult though. Curly

I would LOVE to see the MPG at lower speeds as well, my gut says there has got to be an ideal MPH for mileage, and your chart shows continual gains down to 55.

I just got my 2008 LS 2.2 5sp AA5 two weeks ago. I forgot to reset the DIC after the first tank, so for the first 2 tanks I got 32.1MPG average, at 35MPH average. I'm at 35.1MPG and 38MPH average after about 100 miles on the third tank. This is a mix of around town and highway, probably 40/60 overall so far.

I'm seriously impressed at the MPG I can get out of this car (truck). The DIC makes it impossible to not pay attention to my right foot. My other cars are big V8 sports cars, so I'm used to getting 10-15MPG, and not caring how hard I accelerate. The DIC scolds me every time I put my foot in it with the HHR, so I'm that much more aware of my driving style.

Curly, I'd also be interested in an all windows down at 75, and 55 data point. I suspect it will be more of a drop than the A/C, judging by the buffeting I feel.

Jonathan

With the air conditioner off and all the windows down may act like a "Parachute" and may not be much better than with the air conditioner on and windows up. Just do not know.
I did a short run with the windows just cracked and the air conditioner off it was VERY hot and noisy but the mileage went up from 37 to 44. I want to do more testing on this as I do not quite believe or understand those numbers. Freeing up horsepower will help the mileage but 7 MPG!!! That is a lot!

As for testing below 55, I do not know of anywhere that I could safely go that slow with out getting run over. It was tricky at 55.

It will be winter before I do much more testing with out the air conditioner!

Interesting thing is I believe the lowering kit will help me about 1-2 MPG at the higher speeds like 65 plus. It is going to be hard to defintavly prove with so many variables though...

My other truck is 1 ton four door Chevy Duallie and it gets about 6 to 12 MPG depending on the load I am pulling. This HHR has cut my monthly fuel bill to 1/4 of what it was.
I love the AA5 option, that is the only thing I really wanted in my car and did not get.

I also agree the DIC makes me pay much more attention to my mileage and want to do better.

I would LOVE to see the MPG at lower speeds as well, my gut says there has got to be an ideal MPH for mileage, and your chart shows continual gains down to 55.

I just got my 2008 LS 2.2 5sp AA5 two weeks ago. I forgot to reset the DIC after the first tank, so for the first 2 tanks I got 32.1MPG average, at 35MPH average. I'm at 35.1MPG and 38MPH average after about 100 miles on the third tank. This is a mix of around town and highway, probably 40/60 overall so far.

I'm seriously impressed at the MPG I can get out of this car (truck). The DIC makes it impossible to not pay attention to my right foot. My other cars are big V8 sports cars, so I'm used to getting 10-15MPG, and not caring how hard I accelerate. The DIC scolds me every time I put my foot in it with the HHR, so I'm that much more aware of my driving style.

Curly, I'd also be interested in an all windows down at 75, and 55 data point. I suspect it will be more of a drop than the A/C, judging by the buffeting I feel.

Jonathan

I did not notice any significant gain going under 55 on the highway, one of my first long trips with this car on the highway at 58mph average (cruise 90% set at 60mph no hypermile tricks) was 36.1mpg. With out any tricks, I dont believe I can do better than 37-38 at 55. Going slower will just eat up fuel when a climb comes, also I think that the engine is more efficient at higher rpms, so the inflection point between best mph and mpg falls around 55. You 2.2's probably run a higher rpm to drive 55mph, so you should get a couple of mpg better than me at 55, but you wont se a gain probably going 50.

My car got 39.7 @ 55 and 37 @ 60 so that is very close to your 36.1 @ 60.
I was pleased with 35.7 @ 65 miles per hour, that is decent mileage and still not going too slow. I agree there probably is not much if anything below 55. With my car right now the "Sweet Spot" is probably around 60-65 where it gets good mileage and anything more than that goes down from there.
I still want to do more testing because I felt it should have been more consistant.

I installed a K & N filter but do not have any results yet. I went out on a test run last night but was not impressed with results.
The mileage appears to be down about 1.5 MPG but the weather conditions are different. When I did the original test run it was at 437 feet above sea level. Last night it was 772 that means the air is much thinner due to the hurracaine coming in also there was a little more wind. We should be getting several days of rain here in the United States of Texas so it may be a few weeks before I get reliable information. I am in Dallas so there is no danger here but conditions certainly will not be great for a while.
One other thing to note is that opening up the intake and exhaust may not help in fact it may hurt the mileage until it is tune and calibrated to the higher air flow. The Mass Air Flow sensor and O2 sensors on exhaust are supposed to tell the computer what is the best mixture but it still should be tuned for new parts. Definaty those things will hurt mileage if I run the car harder.
Another surprising thing is in my short run last night the car got 8.5 MPG better with air conditioner off and windows up. I am trying to free up horsepower to get better mileage with out turning off air conditioner.
I will keep you posted on the results as I get them. Curly

I did another test this morning before the rain started. The results are more confusing. While the temperatures have been fairly consistant some of my results are way different than expected and not able to repeat.
Last night I got 34 MPG @ 60 MPH hour which was way lower than I expected. This morning conditions were worse and I made the SAME 12 mile run at the same speed and got 40 MPG! Why?
I tried it with the Air conditioner off and got only 38 which was terrible! Last time I got 44. The only difference I know of is the run with the air conditioner off was the first run on a cold motor and drivetrain.
After it warmed up I got better mileage with the air conditioner on. I wanted to try it again with the air conditioner off but it started raining.

With my race car I could pull the car off the trailer, warm it up, check the weather gauges and calculate almost exactly what the car would run.

With this car there does not seem to be much consistancy so it is hard to tell what is going on, what is an imporvement and how much.

For instance I got 7 MPG better last week with air conditioner off @ 60, last night got 8.5 MPG better and today I got better mileage with the air conditioner ON! What up wit dat? The overall mileage was a little worse this week with the K & N filter but it was MUCH more humid this week due to hurricaine and rains coming.

How I have been testing it is to get the car up to the test speed, set cruise control, reset average MPG and run it for about 13 miles. Last night and this morning I drove the same road, exact same miles and similar conditions (until it started raining) and got different results?

One run was better than last week with the stock filter but one was worse. So I do not know what to think.......

I installed a K & N filter but do not have any results yet. I went out on a test run last night but was not impressed with results.
The mileage appears to be down about 1.5 MPG but the weather conditions are different. When I did the original test run it was at 437 feet above sea level. Last night it was 772 that means the air is much thinner due to the hurracaine coming in also there was a little more wind. We should be getting several days of rain here in the United States of Texas so it may be a few weeks before I get reliable information. I am in Dallas so there is no danger here but conditions certainly will not be great for a while.
One other thing to note is that opening up the intake and exhaust may not help in fact it may hurt the mileage until it is tune and calibrated to the higher air flow. The Mass Air Flow sensor and O2 sensors on exhaust are supposed to tell the computer what is the best mixture but it still should be tuned for new parts. Definaty those things will hurt mileage if I run the car harder.
Another surprising thing is in my short run last night the car got 8.5 MPG better with air conditioner off and windows up. I am trying to free up horsepower to get better mileage with out turning off air conditioner.
I will keep you posted on the results as I get them. Curly

I watch my inst mpg, and it seems that the air conditioning hurt while accelerating. Not so much why in the flats on cruise. I notice little decrease with th a/c on, maybe 1.5 mpg, but i have never drove extended time with the a/c on in the city. That stop and go might really add up with the compressor on.

I did another test this morning before the rain started. The results are more confusing. While the temperatures have been fairly consistant some of my results are way different than expected and not able to repeat.
Last night I got 34 MPG @ 60 MPH hour which was way lower than I expected. This morning conditions were worse and I made the SAME 12 mile run at the same speed and got 40 MPG! Why?
I tried it with the Air conditioner off and got only 38 which was terrible! Last time I got 44. The only difference I know of is the run with the air conditioner off was the first run on a cold motor and drivetrain.
After it warmed up I got better mileage with the air conditioner on. I wanted to try it again with the air conditioner off but it started raining.

With my race car I could pull the car off the trailer, warm it up, check the weather gauges and calculate almost exactly what the car would run.

With this car there does not seem to be much consistancy so it is hard to tell what is going on, what is an imporvement and how much.

For instance I got 7 MPG better last week with air conditioner off @ 60, last night got 8.5 MPG better and today I got better mileage with the air conditioner ON! What up wit dat? The overall mileage was a little worse this week with the K & N filter but it was MUCH more humid this week due to hurricaine and rains coming.

How I have been testing it is to get the car up to the test speed, set cruise control, reset average MPG and run it for about 13 miles. Last night and this morning I drove the same road, exact same miles and similar conditions (until it started raining) and got different results?

One run was better than last week with the stock filter but one was worse. So I do not know what to think.......

Your mileage will vary alot based on simple driving differences with each drive. My work to home drive is precisely the same route every day. I've scrutinized more than 50 drives of that same route. The best mpg i recieved was 44.2mpg the worst 35ish. That is 12.2 miles 75% highway 25 city. The 42.1 was from work , however i went to the gas station before I went home, I started the inst mpg once i passed the driveway of my job again, minor hypermile tricks, that warm up helped my economy alot. From a cold start with full hypermile tricks, I was able to get about 44-45mpg on my return trip home. I wouldn't try this if traffic was heavy, or during inclimate conditions, but its not hard at all.

My point is that you will always see a varing mpg of 3-5mpg no matter if your trip is to/from the same place and the temp/conditions seem exactly the same.

I understand why there is some differences so I did one of the tests on the same road both directions right after each other.

With my race car I knew exactly what the car would run and why. Wind, humidity, temp, Barametric pressure, altitude all of those thing effect peformance along with driving.
If I made back to back runs with my race car they would be almost identical. The car would pick up or slow down a lot with the weather same as mileage and performance on my HHR will but it should have some consistancy and reasoning. This does not seem to have it.

I understand why there is some differences so I did one of the tests on the same road both directions right after each other.

With my race car I knew exactly what the car would run and why. Wind, humidity, temp, Barametric pressure, altitude all of those thing effect peformance along with driving.
If I made back to back runs with my race car they would be almost identical. The car would pick up or slow down a lot with the weather same as mileage and performance on my HHR will but it should have some consistancy and reasoning. This does not seem to have it.

Is your race car an HHR?

My Race car is a 67 Camaro drag car on alcohol with a small block Chevy. I usually raced at the Texas Motorplex in No Electronics class. I learned a lot about performance, weather and how it effects your car.
My race car is pretty much set up and stays that way unless there is a major weather change I might tune it some.

In my opinion the new cars should be even more effected by weather since it automatically adjusts fuel to the air coming in and the Oxygen level going out. Better air= more fuel= better performance. It is supposed to have the perfect fuel mixture in different altitudes, weather conditions etc.
Still I should be able to get some sort of consistancy to tell what the mileage is and how much it improves it or hurts it.

Ok, Here is an update. I lowered the car a while back, I put a front air dam on and I have put taller wheels and tires on it. I put an Airaid intake on it a few weeks ago. So far with all changes my mileage is up about 4.5 at highway speeds of 60 to 75 MPH and about 2-4 in the city driving. Results are not as consistant as I expected and there are some strange numbers on some of the runs but the improvements are showing.
My next mods will probably be the exhaust system then Trifecta tune and then underdrive pulleys. I am also going to make a few more cosmetic changes. The grill will be painted to match car and the little black plastic piece below grill will be painted. Considering a rear spoiler.
My goal was 5 MPG in the city and 10 on the highway and it appears that I may reach that goal. Trying to make one change at a time to verify each good or bad. On the exhaust I am going to replace entire down pipe and everything as one and keep complete stock system so if I have to I can go back and verify any changes. In fact I am keeping stock wheels, tires, intake and everything.
I do not believe I will get the full benefits of the intake and exhaust until I get the tune to match the fuel and ignition curves for the better breathing.
I do think it is on track to reach those goals and will let you know more as I learn it. Some people disagree with me about the exhaust and intake but if I am wrong I will post that too. Not the first time I have been wrong and certainly will not be the last time. No matter what happens my car is looking better, it is more fun to drive and I am saving a whole bunch over my One Ton Four Door dually I was driving.
http://i413.photobucket.com/albums/pp217/airetexbruce/P9291296.jpg

looking good bruce. keep us updated

Heres a thought..minus the performance and wow value..it will take you approx 6.8 years for all those mods to pay off...hmmmmmmmmm

I do not care how long it takes, when the car does what I want it to I will enjoy it mare and that is why I am doing it. To me a car is more than just something to get from point A to B.

I do not care how long it takes, when the car does what I want it to I will enjoy it mare and that is why I am doing it. To me a car is more than just something to get from point A to B.

i agree bruce. keep up the good work bro. how you like the intake?

saying a car is just transportation is like saying sex is just reproduction. :bow:

"i agree bruce. keep up the good work bro. how you like the intake?"

I like the intake a lot. I am getting about 2 MPG better in the city and 2 on the highway. Not a huge difference but it is a step in the right direction. I think the car runs a little better and definatly sounds better.

As I said in my earlier post I think when I do the exhaust and Trifecta tune it should all work together for better mileage and performance.

"saying a car is just transportation is like saying sex is just reproduction."

I am not going to compare my car to sex but I do enjoy it more now than stock and it is more than just transportation.

"i agree bruce. keep up the good work bro. how you like the intake?"

I like the intake a lot. I am getting about 2 MPG better in the city and 2 on the highway. Not a huge difference but it is a step in the right direction. I think the car runs a little better and definatly sounds better.

As I said in my earlier post I think when I do the exhaust and Trifecta tune it should all work together for better mileage and performance.

"saying a car is just transportation is like saying sex is just reproduction."

I am not going to compare my car to sex but I do enjoy it more now than stock and it is more than just transportation.

well glad your enjoying it man. we need to hang out again, me u n andrew

well glad your enjoying it man. we need to hang out again, me u n andrew

Yep, We need to meet up some cloudy overcast day somewhere nice looking like a lake or park so we can get a bunch of good pictures of our rides.

Don't get me wrong..I'm all for it. Been doing it for years..I concentrate on the performance side of things. That will generally net a milage increase. More power equals less petal which usualy means less gas.and this will hold true up to a point,then your power increase will require a fuel use increase...but then again, its all in how you use that power..wink

Don't get me wrong..I'm all for it. Been doing it for years..I concentrate on the performance side of things. That will generally net a milage increase. More power equals less petal which usualy means less gas.and this will hold true up to a point,then your power increase will require a fuel use increase...but then again, its all in how you use that power..wink

I agree with you 100% and could not have said it better. Now there are some here who dissagree and after all of my modifications and testing I will let everyone know the results. All of my mods I am doing for better mileage if if it perfoms better to then I have no problem with that..... Wink.
Horsepower definatly takes gas but intake and exhaust restrictions also cost gas and horsepower.
Water pumps, alternators etc also cost performance and mileage. We have to have them but I can get an underdrive pulley to reduce the losses some. Curly

Ok, Here is an update. I lowered the car a while back, I put a front air dam on and I have put taller wheels and tires on it. I put an Airaid intake on it a few weeks ago. So far with all changes my mileage is up about 4.5 at highway speeds of 60 to 75 MPH and about 2-4 in the city driving. Results are not as consistant as I expected and there are some strange numbers on some of the runs but the improvements are showing.
My next mods will probably be the exhaust system then Trifecta tune and then underdrive pulleys. I am also going to make a few more cosmetic changes. The grill will be painted to match car and the little black plastic piece below grill will be painted. Considering a rear spoiler.
My goal was 5 MPG in the city and 10 on the highway and it appears that I may reach that goal. Trying to make one change at a time to verify each good or bad. On the exhaust I am going to replace entire down pipe and everything as one and keep complete stock system so if I have to I can go back and verify any changes. In fact I am keeping stock wheels, tires, intake and everything.
I do not believe I will get the full benefits of the intake and exhaust until I get the tune to match the fuel and ignition curves for the better breathing.
I do think it is on track to reach those goals and will let you know more as I learn it. Some people disagree with me about the exhaust and intake but if I am wrong I will post that too. Not the first time I have been wrong and certainly will not be the last time. No matter what happens my car is looking better, it is more fun to drive and I am saving a whole bunch over my One Ton Four Door dually I was driving.
http://i413.photobucket.com/albums/pp217/airetexbruce/P9291296.jpg
If I may suggest... White color seems to me to be that rare exception that goes well with the "chromed" grill. Short of going the SS route of course:D