Where did my gas mileage go?


Senior Member
I let my mother borrow my civic for a couple weeks while her car was getting the transmission replaced. When I got it back I noticed that my gas mileage went down from 38 - 40 now down to 30 - 34. The spark plugs and wires are not even a year old, so I don't think they are the problem. Any other suggestions?


I wear stretchy pants
dirty air filter, fuel filter,plug wire, just throwing things out there for ya


Senior Member
Hmmm since the plugs and wires are new I doubt those. I checked the air filter and its still a beautiful K&N pink. Fuel filter good idea, I will look at that.


is your check engine light on?
hows your tire pressure?
drive around with lots of braking then stop and feel for a wheel thats hotter than normal = sticky caliper...

all these things, plus the things mentiopned above can affect your mileage...
what gas do you run, and what gas did she run?
you can always fill up with 91, get the car warm and reset the ecu, then drive it again to get the ecu recalibrated to the 91 octane...


Member of the 20 nut club
cat could be on its way out
O2 sensor could be on its way out

both fall far out of their efficiency range long before they set off a check engine light