Well it looks like I'm going to add to the list of poor mpg posts....I'll start with the basics...
I just bought the car a few weeks ago. It's a 05 ZXW 2.0l 5spd with 105k mi on it. Tires are inflated to 41psi front 39 rear. No brakes are hanging up. Tires are in good shape about 2/3 tread life no funny wearing. No DTCs/ engine light is off.
I installed new spark plugs( autolite ap103) last week along with a fuel filter and fuel tank (had a pinhole leak)
, I've also cleaned the MAF. I'm not a lead footed driver, I accelerate slowly and shift at 2,500rpm. On a trip the other week to Wisconsin from Grand Rapids MI using cruise and at 70-72mph I average 28mpg over 3 tanks of gas. At home on my regular commute filling at the same gas station at the same pump I've been getting 25mpg (no ac use either). My driving route is 1Mi city/ 46Mi highway each way... I'm thinking I have a problem, I am throwing no codes but the car is idling around 250-300rpm (Going to clean IAC tonight). I'm going to try getting the reflash done on the PCM next week and a 3M high pressure fuel injection cleaning later this week. I've been running some injection cleaner in the tank as well.
Does anyone have any other thoughts on what else might be going on? I know its cold and winter gas ect. But I wouldn't think a 7-5mpg drop for that! Maybe its time for a CAI to replace the stock filter?
Opinions welcomed and thanks for the help.