That just seems excessively low. How are you calculating that? What are your rear tire sizes?

I get better fuel economy that that in my 25 year old Mustang. That just seems way too low for a car that someone is obviously trying to maintain well.

 

I'm getting approximately 17mpg summer and an abhorred 13-14mpg during the winter right now. While it's been a fairly bad Canadian winter so far (by recent standards), I have a feeling that the g35x should give better mileage than that. I have a fairly tame driving style, rarely above 2-3k rpm and mostly highway miles as well. This makes me worry about going from stock 17's to 18/19 come summer - the gas consumption might not be worth it. I'll have a checkup come spring as well, but considering I only have <26k miles, I feel like nothing major should be awry.

 

Just for comparison, with my '06X.

I had a 4-day weekend, so i did pretty much 90% city driving.

Not paying attention to gas mileage, loading up my car with 200 lbs of tools/building materials from HD. A couple WOT merges onto a highway....basically not trying at all.

I popped up my NAVI this AM and checked the calculated mileage. It's usually within 1 MPG of what i canculate by hand.

I averaged 17.9 MPG.

Winter gas, 89 octane, 120K miles