Gas mileage was twenty eight mpg and has dropped to seventeen mpg

EMILY_SALMIO

MEMBER
2008 MAZDA 3
2.3L
4 CYL
2WD
AUTOMATIC
170,000 MILES

Hello,

I have the S model, I have owned it for three years. I used to get twenty eight mpg all the time, and now I get seventeen. There are no check engine lights on. To try to remedy the recent drop in gas mileage I have changed all my spark plugs, changed the air filter, cleaned the MAF sensor, ran fuel injector cleaner in the gas tank, and changed the front brakes recently. Can you please give me any ideas as to what I should check, change or do to get my car running better?

1 Reply

HARRY P

MECHANIC
2,291 POSTS

Well this may seem obvious, but if your driving has changed, then your mileage would be effected. For instance, if your driving was mostly highway, and now you are mostly just going short distances around town, then your mileage would go down accordingly.

If the service engine light is on, then I would definitely suggest getting it scanned and getting the codes. You can get that done for free at most auto parts stores. Get those code numbers and post them here. We can look them up and see what is what.

Aside from that, you might try changing what fuel you use. Fuels with high amounts of ethanol (15 to 20%) may not deliver the same fuel economy as fuels with low amounts (10% or less). I do not guess that would make up that big of a difference though.

Also, you may have been on to something with changing the brakes. If the brakes on one or more wheels are sticking slightly, that would definitely affect your mileage. I suggest the next time you drive the car several miles, check the temperature of your wheels when you get out. If one or more of them are really hot (almost too hot to touch) then there is a problem with the brakes there.