I have been driving my 2009 HHR for 9800 miles. Throughout this I have kept the Average Fuel Economy reading up on the Driver Information Center. I reset it every time I fill up. I have always had about 22 mpg in city driving. In the last few months it has dropped to 17 mpg with no change in my driving habits. I took the car to the dealer and they said they could not find anything wrong with the fuel trims or computer codes , yet I am sure the car has dropped in fuel economy. Any ideas as to why this is happening would be appreciated.

 

Summer time, running the AC?

 

Running the A/C really makes a big MPG difference in these cars... especially in city driving. Both my SS and old 2LT lost 3-4MPG easy.

 

MPG is mostly dependent on driving techniques and where you ae driving. Highway driving I routinely get over 32 mpg, but around town maybe 25 mpg. I find that the DIC reads low on average MPG, so I do manual calculations. I have over 69K miles on my car and have never seen mileage below 22 mpg in the 4+ years of ownership

 

I would manually check it. My DIC was reading about 22-24 but when I calculated it it was more along the lines of 28-32

 

Check your air filter change your fuel flitr

 

a long with the other stuff check tire psi and tire wear and supention parts, Go back to the basics and then dig into the hard stuff. Always go start with the basics.

 

Did you switch fuel suppliers? I consistently get better mileage from BP fuel than from the off-brand across the street.

 

hhr's don't have a fuel filter. the only fuel filter it uses is sock type filter on the end of the fuel pump in the tank. The air filter is a good idea though.

 

What? Whose idea was that?