'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.

 

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.

 

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.

 

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!