All I know is this... The important factors are clean air filter, oil changed at the right intervals, Tire pressure, blah blah blah..... However if you have a CEL more so for an o2 sensor, I would point all blame to that... I dont care if someone proved that the CEL had 100% nothing to do with the bad mileage I will still blame it on that... The main reason I have kept this car instead of getting a CX7/MS3 is the fact that my gas mileage rocks compared to those car....and I like that handling feel better but anyways.... get the mil elimenator or something, if your basic maint is up to par, you gotta get rid of the CEL and elim that 02...
Just like HondanoMore said, I can't believe the mileage some of you are getting!
I am suprised too, just in the opposite fashion.... 17-18 avg? thats effin lame... Its like having the gas mileage of a freaking Corvette but being horribly slow in comparison