What are your wheel specs?
As far as rubbing, didn't have to do any mods, it rubbed a bit on the inner "felt" liner but it wore away a bit so it's no longer a problem and that was a couple years ago.

 

Fronts are 19x9 +25
Rears are 19x10 +30

I'm lowered on Eibachs so they all tuck a little bit.

 

NYer chiming in....

I too get the worst gas mileage in the world. You are lucky to even get 18mpg, ever since purchasing this car used I haven't got more than 14 mpg!

Went to the dealer and they of course blamed it on a lead foot. I may change the coil packs/plugs but for 60K miles, this car shouldn't need it yet.

BTW, I do drive aggressively. But it could have also been to a bad clutch?

Using the active MPG in the dash, I can get 20mpg on the highway. Thats the highest I ever got and it was short lived (NJ Turnpike)

 

I don't think it's the clutch in my case, it seems to be grabbing fine and it never slips. I haven't replaced the plugs yet but I have them and I'm gonna do it soon. Maybe it has to do with NY and the type of traffic and driving around here? I don't know anymore, I've pretty much accepted it haha.

 

Please chime in when you do change the plugs. I may go that route if you get better mpg.

 

Replaced them about a week ago and went through a full tank. I'll report back when I fill up tomorrow.

 

Same boat as you im getting between 12-14 mpg and car is very slow! Definitely let us know.I already cleaned throttle body and it didnt make a difference at all.I ordered my spark plugs online and will install as soon as it arrives

 

Install was very easy, you'll have to remove the intake tubes to get to some of them and I removed the whole TB just to get to cylinders 3 and 6, but the whole thing was under and hour.

I just filled up today so I'll let y'all know how the MPG goes...

 

Got let go from my job about two weeks ago. With no freeway driving my MPG dropped from 21 to 16 in a heartbeat.

 

how many klm do u guys get to a tank ?

 

I average about 370 miles to a tank or 595 km. That usually leaves me about 1 gallon to fill up with the 2 gallons in reserve.

 

Mine usually says 230 miles before empty

 

The results are in! I got...

18 MPG

I guess it's just the type of driving I do. Oh well, it can never hurt to replace the plugs.

 

well i just put gas in my car. ..From a full tank down to where it said 50 km till empty...i got 540k...and the numbers in between the gauges said 10.7...i also drove on this tank..200k strait hwy the rest was mixed..hows that for millage guys?...looks like a average of 21,22 i guess?..i just changed the air filters and will do the cabin filter ,,,cars got 138,000 on it 2009 g37x...mint shape..great shine..wonder if its got the scratch heal paint on it...dose anyone know if it was offered on all cars that year?...i do a lot of you tube research on how to fix and maintain this car...like anyone who doesn't cares enough to get dirty...i like the idea of changing the plugs..how much are plugs and where can get them......oh ya im not a heavy foot driver ,,,just a bit off the start..

 

2009 G37 7sp all stock with wider 245/50/17 rubber all around, 40K on odometer, two passengers. From LA to Bishop California, round trip, 65-80 mph light traffic, A/C on in mostly 80-90 degree weather. 31 mpg average. Secret: I'm old, really old. Not worth the extra mileage, trust me. ;-)