Hey guys,

I have noticed my gas mileage drop ever since I changed tires from 235/45/17 to 245/45/17. At first it was minimal, and I knew I was going to get few MPG's with the new tires. Lately, 7 months after having tires changed, I am avg between 13-16 MPG city and 20-24 MPG hwy. Style of driving is like an old lady, I never go into VTEC and do not drive aggressive, my daily commute is only 12 miles M-F. Car has 50K miles on it, air filter needs to be changed and its on my to do list. But is there any suggestions, ideas or solutions you can suggest? 13-16 MPG in the city is ridiculous, it cannot be the tires fault alone for this drop

1. What tires and tire size are on the car? 245/45/17
2. Have you used a fuel cleaner at all yet? Yes
3. What is the air pressure in the tires? Currently at 34 psi on all 4 corners
4. When's the last time the oil was changed? Oil life left on MID? Last weekend, 100%
5. Do you have anything heavy in the car like a sound system? No
6. How hot is it where you live? Dallas, TX .. 50-70 degrees on avg
7. Do you park your car outside or inside? Inside garage
8. What color is your transmission fluid? Not sure, need to check
9. Have you disconnected the battery at all or tried a "gas pedal reset trick" at all? Nope

 

Inflate your front tires a bit more, 36-38 cold. Carry nothing in the car. After a 10+ minute drive, accelerate to 55 MPH on flat ground, 50-80ºF ambient temp, climate control set to Lo and recirculate, minimum fan speed, A/C off, and reset the Trip Computer. Drive a few miles and check the average MPG indicated. It should be in the low 30's.

It's most likely it's not the car, it's the environment and how the vehicle is used. Unless you are tracking MPG's and you notice a sudden massive drop that maintains past a few tanks, I wouldn't be worried.

 

There are hundreds of threads on this. You haven't supplied the useful information. "City" and "Hwy" means nothing. Look at your average mph on the MID. Whatever it is, it probably matches up to what every other TL gets with that average MPH. Mine gets 14mpg but my average speed is only 13mph. It's normal the slower the mph the worse the mpg is.

Air filter makes no difference in mpg, only full throttle power and even that is not likely.

Changing the oil will have no effect on mpg nor will the transmission fluid assuming the trans isn't slipping.

Last, you should be running the highest octane available. 91 at the minimum. The TL has a high compression ratio and it's tuned for best power and mpg on at least 91 octane.

Still though, average mph will make more of a difference than every other factor combined. There's a thread where people were posting their average mpg and mpg. If you can find it you can see where yours stands.

You're driving a 3,500-3,900lb car. It takes a certain amount of power to accelerate a certain mass no matter what engine is in it. That's part of the reason we typically get about the same city mpg as a Corvette that's driven reasonably sane but with double the hp.

 

Thats about Avg MPG for city and hwy, some people get more, some less based on their driving habits.