Gas milage accuracy?
 

How accurate is the average milage display in the car? Mine shows 22.8 average. If I put it on instant it rarely shows 30 unless I an going down a hill. Mostly on the highway at 60 it shows in the high 20's.

I know when I refill the tank, the average is around 1 mpg lower then when I calculate the total Miles divided by gallons at fill up :confused:

My experience has been exactly the same as lvhhrpanel is describing.

Interesting. I routinely see 40 and 50 mpg stretches on slight downhill grades, routinely see the engine go into fuel cutoff mode (99mpg) on decent grades, and get plenty of mid to upper 30's on the flats. my DIC is showing 32.7 mpg overall, and was as high as 33.3 mpg until I had a spurt of rushed city driving last night.

It will be interesting to see where mine settles in once the engine is broken in and running with a belly full of synthetic oil.

UPDATE:

I just filled the HHR on the way to work today. I logged 33.8 MPG by the calculator, The DIC was showing 33.1 mpg. Not bad for a sub 1k mile engine in a combined cycle driving environment.

mpg
 

i found mine to be very accurate...within 1-2 mpg , and never more than 3 off...i used to check it daily , or every other day...i use just a little over a tank every 2 days...i allways used the same pump set on slow fill , then checked on paper and with calculator....i used to allways have my dash thingy set on instant...i just got tired of allways watching it....i still watch it , but i keep it on average now and reset it every time i put in gas , around 8 gal a day for 270 miles....the worse i ever seen it not match my paper/calculator was when i drive it real hard , testing my mods. ..i drove a double shift today , and watched it drop to 26 mpg:eek: , i was driving hard , with ac on , the traffic was heavy and i was in a hurry to get done..

Likewise.

My 2.4 HHR is very optimistic, it states that it is 23mpg when I calc it was 19. I changed out the gas and installed the intake/ecu upgrade so we will see how well it will look.

Just passed 10,000 miles on my 2009 and the DIC said 21.3 and I reset it for the next 10,000 miles. My calculation is 22.7 MPG. Good enough accuracy for me - I don't have any unrealistic expectations of technology.

My records for a 2800 mile trip matched the DIC average exactly.

taking mine to Bristol in a couple of weeks, nice long 1300 mile drive (one way), should be a good test of what kind of mileage I'm actually getting.

'07 2.2L, and mine is never off more than 0.8 - 1.0 mpg.

I must say the milage of this HHR is somewhat disappointing. My DIC is showing an average of 17.9. My daily commute is 34 miles, 30 of which are on the expressway, and I have yet to go over 65. That was with the tank the dealer gave me, E85 maby? I just topped it off and reset it, so I'll see what it really is.

new?
 

if your 09 panel is new , maybe it needs to be "broke in"....some things that increased my mpg were cleaning injectors , new air filter , removing the fuzzy tube (the cold air intake tube), having the correct or thinner than recomended oil , and putting max air in tires....if you are sure all these things are correct , then i would be talking to the gm service people and asking them to check all the tuning...i got 35.2 on the way home this am on rural roads after refueling and resetting the dash thing , prior to that it read 30.2 after some mixed driving with most being on the hwy at 76mph , on my 08 2.4 auto with 92,000 miles.

After 60 miles with what I know to be gasoline, and who drove it average is up to 25.9. The car was in for service twice the first week I had it, and who knows what went on over there.

Now, I've only checked once, but my DIC said I got around 30 or so mpg, and I calculated it to about 27. It's been a while, so I don't remember the exact numbers, but it was 3 off.... But there are so many variables that could throw it off slightly...perhaps even the car was at an angle at the pump and I fit more gas in...who knows. I just go by the DIC, I figure it's good enough, if it's always the same one I check, then I know when I'm at least getting better or worse than what I was.

Mine's an optimist
 

My '07 2.2 5-speed is consistently higher than what the miles/gallons math indicates. It's usually about 1.5 higher than what I calculate after filling up. I've been keeping a spreadsheet which records the car's estimate and the calculated plus a cumulative average of total miles/total gallons which is currently 32.9.

My DIC reads about 2 mpg lower or more than calculated values. Before the ethanol blends, I would see some 38 mpg when on the road. Anymore, I'm lookng at maxing out at 30 mpg over the same route. However my overall average is about 30.5 mpg and has been slowly dropping. (I do lots of highway driving) After ~54,000 miles, maybe some need of a "tune up".

Mine is exactly what I calculated, so after that happened the first 4 times I quit checking it. I've seen it say 36.9, after about 260 miles with the cruise control on the whole time, but then I drive like an old lady on downers. It seems to have something to do with having a stroke 3 years ago.

My wife takes the estimate as the gospel truth sometimes. I look at it but don't pay too much attention to it. I would believe it if I were driving the same speed under the same conditions everyday... but I don't.

Which intake / eco upgrade?
 

I am just getting around to manually checking my 40k '07 (love it, love it - had it 2 months)mileage. but my sense is that the DIC MPG is basically clueless. It tells me that I am around 21-23 when raw info about fill-ups says I am in upper 20's.

Question is, I would like to get a bit more HP AND up the mileage some. I think the K&N is obvious for HP but will this improve economy? If I had to chosse 1 device to improve the mileage without sacrificing engine life or HP, what would it be?

Thanks from anyone who cares to respond!

My 2.2 DIC seems right on, I checked it with manual check for months after I bought my HHR this past spring. On the low side I average 32.5mpg and if I travel the speed limit 36-37mpg consistently.

My DIC is awesome!
I'll never, ever go without one again.
The DIC mpg reading is always within 1 mpg and usually within .5 mpg

About E85 -
I was at the stealership today and noticed considerable difference in est. MPG between E85 & real gas.
Over 100 miles difference per tankfull IMSMC

FYI mpg on my 2001 Corvette with 21,000 miles.

Attachment 31922