I know folks, it's an Old Topic. But all of a sudden my G35X, Auto tranny, with 16k on the clock, this winter is yielding only about 11 mpg. Granted all local surburban driving 4 miles each way to & from the train station, but last year I was getting about 12-13 in similar conditions. I don't let "er sit warming up for too long in the cold mornings or when returning home. Is it b/c its colder this year (NY Metro area) or is it a worse "winter blend" of gas. I tried different gas - always used Shell premium, tried BP premium [2 tankfuls, same results]. New air filter installed 2 months ago by Dealer (uummm I should check that out now that I'm thinking about it)... Any other similar experiences or ideas??

 

Hmmm, you'll definitely get lower mileage b/c the car just doesn't have time to warm up so the 'average' mileage will be off since the mileage is so small and the engine is so cold. If you drove it for more miles after warm-up you should see the mileage go up.

I live a few miles from work and only get about 17mpg due to this reason.

I'm not sure, however, if you were getting better mileage last year with the same trip. That's a head scratcher. I think you are looking at the right things though. Could be blends of gas, definitely check the filter. Did you get any ECU updates done or anything like that? Spark plugs? Air pressure in tires (this will defnitely go down in colder weather).

I'm sure you thought of these things but the 12-13 mpg you got last year seems very low as well IMHO.

Please let us know if you figure it out!

Jay

 

Jay: Yep checked those things. Had the TSB 028 applied last year for the Touch Throttle issue. I think that did affect the mileage a little (maybe a small increase), but I just had the Tranny Valve Body replaced under warranty (hard shift into 3rd gear, now corrected with this work). I'll see if that affects mileage any... I think I'll check for that "new Air filter' was actually done. Had 15k service done and that was part of the charge....

 

i think a driver member just needs to take a ride with you and see how you drive...it just sounds like you have a heavy foot...im getting about 15-16mpg with "normal" driving, so i could easily see how you're getting 11 or so if you're driving it kinda hard

 

Sounds like you've checked some of the obvious stuff.

What about tires? Have you checked them in the cold weather? Try setting the pressure at 34 PSI. Pressure might have dropped 3-4 PSI without setting of the TPMS sensors. A drop in pressure may cause increased rolling resistance from a soft tire. Doubtful at 16K but did you change tires? Do you have snow tires on this year for the first time?

Are you drag racing to the train station this year? Just can't keep yourself from teaching that kid in the Jetta a lesson?

 

im in upstate, ny (albany) just picked up an 08 g35x in december. im averaging 16mpg and i work 5 miles from home.

 

Could be many things but to me it sounds like you have short comute and you maybe warming it up too long. How long you warm up the car? I can get same mpg if I warm up my car for 5 minutes. I drive just like you 4-5 miles to work and mornings 2 miles to take y son to the school. If I only warm it up for 1 minute it goes up to 14-15 mpg. If my wife drives it goes up to 18-19 in winter and 24-25 in summer in city.

As someone said before check your tire pressure also. It can affect your mpg badly.

 

I live 2 miles from work. I've averaged anywhere from 12mpg to 17mpg for a tank of gas depending on how spirited I was feeling that week. It's not the car.....it's your driving. Lay off the gas when you start rolling, avoid hard brakes, and it'll come back up.

 

TN G35S: I've tried all of that. I don't warm 'er up too long at all. Tire pressures at 33 - the specs for the tire. I will try to pump it back to 35 lbs , but I "feel" the difference in the ride - gets to harsh for my liking especilally with 16k on these Goodyear RSAs.
tg1234: You get 24-25 mpg in summer CITY driving??. The car's only rated 17 mpg in CITY/ 24 Highway MPG by the EPA? I've gotten 23-24 on the highway in Summer while "feathering" the throttle.

 

Not me my wife. I only can get 18 ish mpg in city. But my wife never goes over 3k rpm. LOL I feel like just get out from the car and walk. LOL She only drove it for a week and she was in city all week got over 24 mpg. It was lite city driving but dropped my jaws for sure to see that mpg.

Myself not getting maybe 18-19 on hwy LOL. I would love to see what my wife can get on hwy. I would think around 27 ish is achivable with her driving. Woulfd be a boring drive tho.

 

I would be lucky to hit 24 on the highway hahaha.

 

Nah with the driving like that. No thanks. I bought the car to enjoy it. LOL

 

You aren't alone. I average 11-12mpg in the city exclusively but it's because I love to drive wild. When I mix city with freeway I average 16-17. On long trips I average 20-22 on the freeway exclusively.

 

^ just like me!