i would also reset the ecu using the pedal method. You can search for how to do it on here.

 

What is a MAFS? Mileage is 74,000

I'll def try plugs first I think

 

Trust me I've driven 2000 miles and checked many times, it's bad mileage.

 

Thanks for your detailed reply I'll definitely check out those ideas.

 

^ MAFS is the mass air flow sensor located in your inpipe to your throttle body.. Its a little black senor, I think on the right.. You can look up diagrams if you need to.

 

I got the same problem, it also does 9 mpg but, drives fine, air filter clean, clean maf sensor. It does have a p0024 engine light could that maybe contribute to the problem. The engine light doesn't limit the car in any way though.

 

Do you get winter fuel over there ?? It's fuel that the snow regions use to help fuel mot freeze. If so, that will be a good idea for bad fuel consumption, also you letting the car idle to warm up ??
check the o2 sensors

 

Guessing you have a V36 chassis since your description says you have AWD and the V35 chassis didn't have exhaust timing on the AWD models.

An HR engine getting only 9mpg is definitely a problem unless you have a really heavy foot. How many tanks of gas have you measured to calculate your MPG, and you're doing ACTUAL MATH right not just going off the onboard MPG display?

 

I haven't checked doing the actual math but it sure does feel like 9 mpg since my fuel gauge drops so quickly, so far I have tried to clean maf sensor, and new air filters but nothing seemed to work. It also runs perfectly, so I am confused about why the mileage is so bad. It does have a p0024 engine code though, could that maybe contribute?

 

Gotta track actual mileage, you can't just "guess it's getting 9mpg". Fill up the tank, reset the trip odometer, drive until it's about 1/2 full, fill up again, check how many gallons it took and divide the trip odometer miles by the gallons consumed.

Usually the G35 gets like 13-15mpg city, 20-23 highway.

That code is for the exhaust cam magnet retarder, it shouldn't have that much of an impact on mpg.

 

I did the calculation and got 8 mpg one lower than the onboard display. I'm confused because my car runs perfectly.

 

I'd start with fresh plugs and air filters

 

Hey, I have a 2004 g35 coupe and also a 2006 coupe, I'm having the same problem with both cars,
my 06 I'm getting about 220km to a full tank that's 130 miles ​​​
my 04 isn't to much better I'm getting about 390km on a full tank. The exhaust pipe is Black and if I stomp on the gas since I have a small exhaust leak my entire car fills with smoke.

Oil is another huge issue, on average im putting a litter of oil per 300km . I've been to a point of having less then a 1/4 coffee cup of oil left in the car and no oil light came on.

I did some searching on line and found some very interesting things about this car. Infiniti recalled a select run of cars baised on the v.i.n regarding oil consumption issues . Which is strange because this is were the fuel problem kicks in, if your car is using a high amount of oil your gas use will increase, which will destroy your engine. Unburnt gas will eat your seals and valves and start leaking into your oil. Then after time you start hearing rattling once hitting about 3000 rpm that's when your engine is on the way out. The interesting part of this story is Infiniti knows of the issue, and simply said oh well and made a small recall to make it look good. But when in fact every v6 3.5 engine from 2004-2006 shouldve been recalled.

how many g35 or and 3.5 from 2004-2006 do you see on the road in good running (engine) shape over 300,000km. . Most I've seen at 250,000-300,000 are in the junk yard

 

These engines run fine drinking oil, the reason they're in the scrap yard is the owner didn't check the oil and ran out Most seem to die from natural causes at around 200k-250k miles which seems normal. Yours however does appear to be having problems, it should not smell like exhaust inside your car, nor should it be blowing smoke out of the tailpipe.

The Infiniti oil consumption recall only applied to the rev-up engine iirc.

My gas mileage is dependent entirely on my right foot, I can get it down into single digit mileage but if I'm TRYING to get good mileage I can manage about 15mpg city and 20 highway.