Originally Posted by Dackelone
Well... what about the usuall suspects: air filter, tire pressure, spark plugs, fuel brand and type (octane)...
Speaking of fuel type... how much ethanol is in your fuel? Those 10% ethonal fuels really cut your fuel mileage.
IF everything is ok, you might have your dealer check for any codes and even have them check the lambda signal value. It should be right around 1.0 +/- 0.2% Perhaps your O2 sensor(s) are bad and the DME is over correcting.
I'll check the air pressure but since we have the free maintenance I'll have the dealer check everything else. I only use Chevron or Shell gasoline so I doubt thats the case.
One thing I have noticed is that when I reset the computer so there is less data to calculate the average mileage I can see a SHARP drop every time I start the car. I filled the car last night, drove it for 30 miles and came home with an average mpg of 18. I started the car this morning, drove it 2 miles and I was down to 16. The engine was then warm and I drove it back home for 2 miles and I was back up to 17. Then I took it to the the aprtment complex car wash and it dropped back to 16 mpg after driving it for 100 yards. I know starting the car takes a lot of gas and so does driving on a cold engine but geez...18 to 16 mpg in 2 miles? wtf