I drive a 2008 g35x sedan. a full tank of gas gives me a range of 170 miles. i got an oil change and did an ecu reset and drove like a grandma. i’m averaging 13 mpg and the trip shows i’ve driven 120 miles and i’m sitting at a half tank. just driving from my home to work and back drops my fuel gauge by two ticks. i’ve gotten an oil change, new air filters, cleaned maf sensors, what else is there left to do

Are u sure your fuel gauge is working correctly?

170 miles on a full tank is pretty bad. U would definitely notice a loss of power or something off about the way the car drives.

i mean it should be, trip odometer shows 120 ish miles on half a tank. and the average mpg is about 12.3. last time i filled up when i was at a quarter i ended up filling about 14-15 gallons. personally i feel like the car drives fine, but it might just be my inexperience with the infiniti platform.

also forgot to mention, as soon as i turn the car on fans kick on full speed. even on the coldest mornings, even if i just turn the power on without starting, the fans kick on. also when the cars warmed up and i shut it off and come back to it 5 minutes later and start it, it’ll run for 2-3 seconds then the rpm slowly falls to 0 and the car shuts off. the only way to counteract it is to feather the throttle so the rpm’s stay high, then the car figures itself out.

If it's all city , it's normal

Something is causing the engine to stall, start by looking for a vacuum leak.

As far as I'm concerned, it's normal to get that sort of fuel mileage. I do 90% city driving and average just under 14. The other 10% isn't really helping the average. 75 mph cruising in top gear is still over 3k rpm so it's hardly an overdrive gear. You gotta pay to play with this high revving engine and antiquated transmission.

bummer, as a broke high school student, filling up half a tank of premium isn’t the easiest. for my other problem do you have any suggestions?

will do, and will update you

YouTube BG Fuel air induction service. I've had this done a couple of times. May help to smooth the idle.

I also have a 2008 sedan, although it is manual and the regular sport model

13 mpg seems about right for city... if youre driving like a jackass and stoplight to stoplight etc.

Once im on the highway/driving like a grandma, around 21~

I also have a Nissan Murano, VQ35DE AWD. City/Highway average WAS 21 for the summer, now its down to 18.5, same driving pattern, but its now winter.


Your fan running constantly does concern me a bit, check your coolant level and for any leaks, my sedan was leaking coolant out of the rear heater hose directly onto the o2 sensor and caused alot of problems.

beyond that, youre going to need to start diagnosing things, such as sparkplugs, injector flow etc.
There are a few similar threads about bad gas mileage that might point you in the right direction

You don't HAVE to run premium, the knock sensor will do it's job and pull timing. Under WOT you will have a little less power.

They stamp premium only on the gas cap because they want their sports car to feel like a sports car, not be underpowered. Plus regular timing retard from the knock sensors isn't great for most engines but these VQ engines literally live on the knock sensor unless the car is tuned and you pull timing off the map.

Most engines this isn't a great practice, the VQ doesn't care though, this has literally been a thing since they day they came out, these engines knock and pull timing even when they were brand new off the showroom floor.

‘07 G35x. I’ve always run 87 since I bought at 105k. 213k now and still going strong.

thanks for the reply, I have yet to diagnose the issue with my car. Just two days ago I topped off my tank and last night my gauge was sitting at quarter tank. i’m beyond frustrated with this car. I assume the car is running rich, it pops when I revv it and the strong odor of fuel is present. Although my average mpg is right around 15 now because i’ve been on the highway more often than not, I still ran thru a full tank of gas in nearly 2-3 days.

ahh. I just run premium for both peace of mind and that little bit of extra drivability. For me saving $10 on a full tank of gas isn’t worth the switch, and I feel comfortable filling premium, although will keep in mind incase I go broke, broke.