My son recently purchased a 1999 Buick Park Avenue Ultra with a 3.8 litre engine with supercharger. Highway @ 65 mph he gets 30 mpg, city driving he's down to 12.0 to 12.5 mpg. We replaced the spark plugs, air filter, and fuel filter with no change in the city mpg. I believe the mpg for the vehicle is 17 to 18 city and 27 hwy. Any suggestions as to why the city mpg is so low?
Jul 24, 2008 at 2:22 PM