I have been checking my fuel mileage(3 times so far) on the HHR and each time the computer gives about 1 mpg> more than what I figure. That's not too much of a difference, but am wondering which is the more accurate? I would think that the computer would do away with differences in the fuel pump at the stations you use and maybe be better to go by.
I've found that the average fuel economy reported by my 02 Impala's DIC is very optimistic compared to reality (2-3MPG more). I tend to fill up at a few different stations around the area here and the trend is the same regardless of the station.
FWIW.
Not on my 07 Cobalt! The computer is always higher conflicting with actual calculated mileage; miles driven divided by gas consumed since previous fill up. I also find this inaccuracy (?) for the Range number. In reality I would not expect GM to set it lower!
Unlikely there are any pump differences. It is very tightly controlled by state and federal regulators unless it is a non retail site. Inventory reconciliation is mandatory.
Corvette DIC runs within a couple of tenths (+/-). Buick DIC about .75mpg better than calculated when I drive--lots of miles on cruise control. ... .5mpg worse than actual when my wife drives --short trips. GMC DIC about 1.5 mpg optimistic.
Punchline: all things are relative and -- YMMV.
-- pj
My 04 Impala is consistently 2 MPG higher than reality, regardless.
My 07 Equinox seems to be dead on - without considering tenths.
Willy
I've found both my cars to be optimistic by 1 -2 mpg. One is GM, the other is not.
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