New wheels/subs = poor MPG? No way..
Hey all, so I got my GT back in early summer and couldnt complain at all about it. Since then she got a few new things:
- Magnaflow cat back (came with car)
- Spectre CAI
- DBS rotors/hawk pads
- SLP firehawks (upgrade from stock 18's)
- Kumho Ecsta 4x 245/40/19
Plus some other cosmetic stuff. Still stock tune, headers, engine components etc. Also to point out I run 93 octane all the time.
I've always gotten about ~17 city ~24+ highway. Always thought that was exceptional since I dont have the lightest foot. But here is where it gets strange.
I installed 4 kicker subwoofers in the car and obviously disconnected the negative battery terminal. At this time I also put on the new wheels/tires at this time as well.
Got everything all set, connected battery. ECU obviously was turned off and I reset all the TPMS senors and filled accordingly. For awhile despite the half of a tank I had in the car the Distance read 68mi to go for a day or so. After some driving it corrected itself but is giving a rather low estimate. Likewise MPG has taken a dip to sometimes under 10mpg city and upper teens on highway. I took the car on a 250 mi trip (should be long enough to relearn again) and got the following averages according to speed:
21.4mph - 11.2mpg
68.2mph - 17.4mpg
72.1mph - 16.5mpg
89.mph - 29.7mpg (this was the really odd one)
Im slightly perplexed here. I understand winter fuel will cause a decrease but did I really just coincidentally get the 1st tank of winter fuel all season as this happened? Should I pull the negative cable again and let it reset? Tire pressure I check consistently and everything checks out perfects (car reads it accurately as well). Engineering mode says AFM is on as normal and I double checked the air filter to make sure all was fine. Maybe I'm just paranoid...any help would be much appreciated. Thanks.