My Gas Milage
 

I drove my HHR from Kissimmee Florida to Kentucky one day and back the next. The best I saw on the gas milage readout was 28.5 MPG. I would have thought a 3100 pound econo car would do better than that.

I have a 1999 corvette and it will do that good.

How many miles do you have on it?
I averaged about 28.5 for the first few thousand miles.
It eventually crept up to about 32 in the summer.

The best I averaged on an extended trip (about 525 miles) was 33.5 from Virginia to Wilkes-Barre, Pa.

It also depends on how fast you drive. I can easily coax mine up to the 40 mpg mark, and have seen as high as 42.5.

Ss?

Do the calculations for mpg. The DIC guage in my HHR runs low. Usually on the highway, using cruise control and driving the speed limit, I'll get 32 mpg or better. Any around town driving kills mpg if you have a heavy foot.

I know there are various thoughts on the DIC accuracy when it comes to instantaneous and average MPG but it's actually pretty accurate and I would expect it to be closer than a hand calculation (although we can fool it pretty easy).

They know the injector size, pulse width, RPM, time and speed. From that they can come up with a dang accurate MPG calculation that isn't related to when the gas pump shuts off when you fill up.

I hacked some of the earlier DICs for some engine swaps a few years ago and I couldn't see any reason their calculations would be wrong. There certainly wasn't a finagle factor in there to make it lie. The fuel remaining was pretty bad though since they had curves of the float assembly based on the fuel tank shape.

No doubt this was long before the HHR but there is no reason to change the method. So far, I haven't seen any difference that would make me think I can't trust the DIC numbers. It's my right foot that I don't trust!

My most recent 10,000 miles(10-20) calculations and DIC are as follows:
DIC said 22.6 MPG
Actual was 23.84 MPG

I log all fill ups so this is easy to calculate.

First 10,000 miles were:
DIC said 21.3 MPG
Actual was 22.69 MPG

On long flat trips at freeway speeds I see on the DIC upwards of 33 MPG and less for everything else.

Grass Valley - Foresthill here.

Going from Foresthill to the valley (Roseville/Sac) and back doing the speed limit I average right at 27. I took the SS to the Bay area and got 31 average round trip doing 70 where it was legal.

I have no complaints!

I'm getting 25.8 in my 08 SS auto. Most of the miles are highway.

Had my SS for a week and a half and with little hard acceleration. I am getting so far 26 with average speed of 24 mph.