I purcahased a 2008 G35 S last year and normally when I fill it up it, the gas gauge goes to full and the display in the fuel economy computer resets to 355 miles on the low end and 400 on the high end. I just took a longer highway trip in it - perhaps for one of the first times - and as the dash gauge went down the display fuel economy aka miles to empty did not change much after 125-140 miles. I filled it back up and now it shows 455 on the miles to empty on the fuel economy display. It seemed to add the right amount of mileage back on meaning I added a little over 6 gallons of 93 octane and it gave me the 125-140 miles back. Still I don't trust that 455 miles to empty anymore and feel it may be overstated by 50-100 miles depending....so although I can watch the real, old school gas gauge; I don't know about the computer miles to empty. I'd like to reconcile the two so they are relatively accurate to each other again. Any ideas? I am not good with cars but I have friends who are; but many don't have cars such as this. The dealership is not very helpful as I did not purchase my car from a dealership. I have had the car since last August, it only has 43,000 miles on it and this just happened yesterday. Is there a reset or a fuse to replace; perhaps a connection to check or something to address in the fuel tank....Or has my miles to empty recallibrated itself based on the more steady pace I set for those 150-200 miles. Just trying to address the concern now and not let something go and have it get worse + others who would drive it would be confused. I know I can reset the fuel economy (average miles per gallon) but that is simple and not addressing this problem. Thanks for any help you can provide...pointing me in the right direction, etc...anything. Much appreciated - Dave

The MPG as calculated by the vehicle computer will change based upon your driving and each fillup.













MPG drop from Hurricane Sandy. No power, long gas lines





The correct way to calculate your MPG is to fill up, drive for a few hundred miles and divide the miles driven by the number of gallons it takes to refill the tank.

BTW I only use regular 87 Octane.
There is nothing wrong with your car



Telcoman

With my lead foot it's a stretch to hit 21 mpg

Miles remaining until empty is a calculation based on the car's measurements of the gas remaining in the tank (gallons) and recent fuel consumption (mpg). The equation is Range = Gallons x Mpg. By "recent", I mean the last few minutes. Depending on the situation (i.e. city versus highway or up hill versus down), mpg can vary substantially. To see how much, watch the instantaneous fuel consumption graph. That will make the range prediction vary just as much. There's nothing wrong or magical about this; it's just arithmetic.

Dave, the car got better gas mileage on your recent long trip and that's why it shows a higher miles til empty. The miles to empty is a calculation that is a good estimate. Depend on the fuel level meter, not the distance til empty.

I've parked at my house with about 30 miles til empty showing. Yesterday the next morning it shows zero miles til empty.

There is a reset you can enter to reset everything on the display and it will begin recalculating all over.

Thanks everyone. So apparently there is nothing wrong with the car; it just recalibrated based on my recent trip. I just didn't think it would do so regarding 150-200 miles or so. It has always shown MPG 20-23...more like 21 and recently it now shows 26-28 which just seemed way too high for my vehicle. I generally only do 50 miles a day and that's total two ways. So basically, I should just let it go, not worry, and watch my old school dash gas gauge if I get concerned. I don't like to let the car run low on gas, but does anyone suggest running it down near empty to help it recalibrate? Thanks again to all! Or should I reset my computer? not sure how to do that, but I am told one can so I was going to start reading up. - Dave

I'd suggest you not run it too low. The car is six years old and no matter what kind of gas was used there is going to be some junk and or water in the bottom of the tank. Normally that won't be picked up but, if you run it extremely low, some can get in the fuel line. Should any get past the filter, you could wind up with a clogged injector.

Starter wrote:I'd suggest you not run it too low. The car is six years old and no matter what kind of gas was used there is going to be some junk and or water in the bottom of the tank. Normally that won't be picked up but, if you run it extremely low, some can get in the fuel line. Should any get past the filter, you could wind up with a clogged injector.

Although I have read opposing viewpoints on fuel in the tank cooing the electric fuel pump, I rarely go below 1/4 tank and then fill up. All gas pumps have filters attached to the pumps.

Telcoman

telcoman wrote:

Starter wrote:I'd suggest you not run it too low. The car is six years old and no matter what kind of gas was used there is going to be some junk and or water in the bottom of the tank. Normally that won't be picked up but, if you run it extremely low, some can get in the fuel line. Should any get past the filter, you could wind up with a clogged injector.

Although I have read opposing viewpoints on fuel in the tank cooing the electric fuel pump, I rarely go below 1/4 tank and then fill up. All gas pumps have filters attached to the pumps.

Telcoman

Over the life of a car, the tank is filled at many different places. Not all stations do a great job of maintaining filters. Some also save money by purchasing fuel deliveries from suspect sources - as in junk and/or contaminated gas. There was a fly by night operator who had a Sunoco franchise in the DC area a few years ago and bought cheap garbage gas every other deliver or so. Sunoco shut off his franchise as soon as they found out, but that didn't help the many folks who had repairs because of the crap in their tanks.

Starter wrote:
Over the life of a car, the tank is filled at many different places. Not all stations do a great job of maintaining filters. Some also save money by purchasing fuel deliveries from suspect sources - as in junk and/or contaminated gas. There was a fly by night operator who had a Sunoco franchise in the DC area a few years ago and bought cheap garbage gas every other deliver or so. Sunoco shut off his franchise as soon as they found out, but that didn't help the many folks who had repairs because of the crap in their tanks.

I purchase almost all my gas here locally



When I travel I only use large truck stops that pump thousands of gallons of gas.

Loves, Petro, or TA



Never had a problem and between both my Infiniti's I've driven over 200k miles

Telcoman