Gearhead

My new 2008 GT is showing too few gallons used on the trip computer. Typical values are as if when I fill-up with 14.7 gallons, it says that I burned 13.6 since the last reset. All the while, my odometer is reading correctly. My trip computer calculates a MPG value that is too high by this 14.7/13.6 ratio. I have two questions:

1. Has anyone else seen this, and if so, was it repaired well?
2. Is the reported fuel flow independent of the engine management?

poldrv

Typically the gas mileage in the S197 mustangs improves the more you drive the mustangs. When I first go mine the gas mileage was 22-23 mpg, now three years later the gas mileage is 30-31 mpg. Your trip computer is probably reading correctly.

69Mach1-409

Never paid much attention to the gallons used, but my est mpg the readout displays is always 0.5-1.5 mpg above what I'm actually getting.

krnpimpsta

Yeah, the pump always seems to show an extra gallon or so than what my trip computer says I burned. I don't know why either.

Cheese302

all i know is that once every couple months it rolls over. because i never reset it

Dysan

Welp..I've got to say that my gallons used in my trip computer has been extremely accurate. *My car has had 85k miles to learn itself and the computer is within .2 gallons in accuracy at this point so I'm extremely happy with it.

Enfynet

There are also innaccuracies in the gas pump, hose, and tank. Depending on temperature and flow rate you might actually get more or less fuel than the pump reads. I would imagine the pump in the car is more accurate than the one at the gas station.

kenb0218

I use the trip computer's value as a guide on how much I need to put in when I fill up. Sometimes I can get a little more, other times less but its usually pretty close. Car was 3 yrs old on the 14th and I'll have had it for 3 yrs on Sunday, the 25th.

karman

Mine always says I have used a tiny bit more than I did (.2 gals or so).
Probably because I usually vacillate between flooring it and cruise control.

Boltzman

I quit trying to figure it out. Simple math does not compute with this so why bother

Falchion

Yeah, I have the same issue. I can put in an extra gallon that the computer says was used. That could be a problem!

nynvolt

99.9% of the time my gallons used matches exactly how much I'm able to fill up.

Ofcourse you have to reset it at each fill up...

Indystang

Mine is accurate too. The gas tank vent sucks though. Sometimes I can get .5 gallons more in and sometimes as much as 1.5 gallons more into the tank. It just depends on the stations shutoff sensitivity in my area. I have had the gas tank replaced also under warranty too.