Lately I've only been getting 14 or 15 mpg, about a year ago I would get more like 17-18 (and I drive the same routes as I did then). I also have the hissing coming from the exhaust and the smell of gas. I'm thinking of changing the O2 sensor but could that be bad even without a check engine light coming on? I guess I'll also look at changing the plugs, wires, cat, etc.

 

ik my 3.4 gets ok mpg any where from 18-27 depending on how its drove.

 

u could have a plugged cat. car seem to be getting quiter? less power?

 

It's hard to tell, but now that I think of it it does sound a little quieter than it did a few months ago. The thing is, I just got it smogged last month, so do you think I still could've passed even with a plugged cat? I'm in CA btw which, as we all know, is known for its **** emissions laws xD

 

they check to see if the system is working correctly and everything is there.
did it just start doing it or was it goin on when u got inspected?

 

Hmm the gas mileage did seem kind of bad already then, I'm not exactly sure if it was the same or not as now. But I've been having the hissing and gas smell for months.