17 mpg, 70% city 30% hwy.
Still breaking in the engine though.

 

yeah at this point I got better mpg from city>highway in my g35.. it's kind of sad...

granted I think I'm driving the g37 a little harder than I did my g35... oh well that's what I get for wanting a sedan...

 

well i did a project using different car of course using my G as the v6 variable car.....it was a comparison for fuel efficiency! i had dynos for all four the 4banger v6 v8 and v12....overall the best speeds for a 4banger "toyota" was between 36mph-43mph the G "WERE ALL INTERSTED IN was rediculously funny because it had 2 efficient values both betwwen th 45-48 mph range the car average 34mpg "thats like a new asphalt road" AND 67-74mph it got 32mpg.....it was more efficient then the v8 and v12 and since it had to ranges it out proformed the 4banger!!!!! my teacher drives a acura 3.5rl he was very satisfied and i got an A

G35 is good at those ranges....but idk how different octanes affect the mpg.....

higher octane burns faster...so wouldnt that be bad for freeway driving...since you only need a fixed amount of fuel for a long period of time....i think 89 would do for high cruising drivers right? i only recommend high octane for in city driving less gas for high speed and the g35 glides so rolling stops can get you in the mid 20's in city.....

 

You would probably get worst mileage with the windows down and the A/C off then the windows up and the A/C on except in slow traffic.

 

he's right it depends on how ur driving. Usually if ur goin over 55 it's best to have the windows up. You almost lose the same amount of fuel to wind resistance. Ps always have your AC on Econ it's stops the compresor from running constantly and that's a gas killer.

 

And with the windows down on my sedan the buffeting will ruin your ears, has to have a large effect on the MPG. It seems to come into play at fairly lows speeds, one of my biggest complaints for a luxury car like this.

 

The best our 07 G35 got was 27 hwy and 19 city. Our 09 G37 so far has a best hwy of 30.5 and 20ish city. We live in a smaller town (50k people) so it's not too much of a parking lot on our roads here The hwy mileage was going 80 mph on pretty flat drives. Oh, and yes, our AC is on most of the time

 

My brand new 09 G37S Journey got 21 mpg city driving on it's second tank. Haven't had it on the highway but would love to crack into the 30's.