I've noticed over the last 3 years i've owned my car that the miles per gallon i'm gettin has decreased. Only thing i've changed is a K&N air filter and a flowmaster muffler. Is there anything that i need to check that would be causing this problem??

 

How many miles are on the car? My car is doing the same thing but I think I need new 02's!

 

Just about to hit 100,000. I've had the distributer and water pump changed, new plugs and wires...regular oil changes, and i need to get my transmission fluid drained and changed. I've heard people talk about a fuel filter, dont really know what that does or if that my have an effect, but all other regular stuff has been done.

 

Well, I'll tell ya what. My 95 Z28 convertible has 165,000 miles on it. It has 4.10s in the rear and M6. On the last road trip (5 weeks ago) I got 27 miles to the gallon on 2 tanks, 28mpg on one tank, I drive it to work everyday (78 miles round trip) mostly highway and average 24mpg. I would say you have a problem.
Ron

 

Yeah, its not too bad on the highway, but has gone down and in city driving its horrible.

 

also....might want to try cleaning your MAF sensor. I used zero residue electric contact cleaner. u can spray it on and let it dry, or can use a q-tip or something and lightly swab it, of course its more risky if you clean it like that cuz you could break something, but if you're careful, it's okay. the sensors in mine were dirty, i cleaned it and now its shiney silver...