The Curly 1

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.

Clevelandhhrss

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.

The Curly 1

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.

The Curly 1

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

The Curly 1

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.......

Clevelandhhrss

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.

Clevelandhhrss

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.

The Curly 1

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.

Clevelandhhrss

Is your race car an HHR?

The Curly 1

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.