How accurate is your MPG computer?

[Dutch]

Mine isn't. It's always off by 1 mpg or more on the high side, and even worse when I'm on the highway. Cruising at a steady 75 mph it claims that I get 28 mpg. Fat chance.

Having an inaccurate gauge is worse than having no gauge.

 

[Hawk03]

I have never tried a manually computed the gpa but I will when I go home next weekend.
I agree I wouldn't know what to do with out that gauge. How low does every one let thier tank get before they fill up. I think the lowest I have gone is when it said "7 miles to empty." But I usually fill it when it starts beeping.

 

[cableguynoe]

You need to stop reseting it and just let it average out. Then i guarantee you wont get 28 mpg.

 

[LS Gets U Wet]

You need to stop reseting it and just let it average out. Then i guarantee you wont get 28 mpg.

Does every year have the message center w/ mpg? Mine doesnt show mpg...but ive let it creep down to 2 miles left til empty. I figure that it has a reserve of like 5 gallons?

 

[jdsimons]

ya i think my speedometer is like 2 to 3 mph off.. for some reason.. Even with the gps speed sensor on the headunit and gps satelite shows my speed about 2 to 3 mps less then my speedometer.. suppose theres no way to fix it.. not real a big issue though i guess will give me a little more room to work with when i'm driving down the highway not paying attention to the speedo.

 

[2001LS8Sport]

On a long trip where it had the chance to accurately average the mileage, mine was dead on the nuts. I found an article once that said DON'T try and outguess it because it was VERY accurate.

 

[ambisonics]

When I first got my car I didn't think it was very accurate, that was because I was having so much fun ripping the car from stop signs and traffic lights. Now that I drive more consistantly (even thought I still rip it sometimes) the city mileage is dead on at 15.9 all the time. Everytime I fill the tank I calculate the actual mileage and I get the same. Sometimes highway trips throw it off a little though.

 

[maxlsv8]

The best MPG I ever got in my car is 19.8 on highway, usually it stays at 16.5 city, but I think that its pretty accurate.

 

[cableguynoe]

0

 

[Dutch]

ya i think my speedometer is like 2 to 3 mph off.. for some reason.. Even with the gps speed sensor on the headunit and gps satelite shows my speed about 2 to 3 mps less then my speedometer.. suppose theres no way to fix it.. not real a big issue though i guess will give me a little more room to work with when i'm driving down the highway not paying attention to the speedo.

You can buy bigger tires. Figure out exactly how far off it is on a percentage basis, then buy tires that are that percent larger in diameter.

On the gas gauge thing, I've checked the mileage on every tank I've used (23,000 miles) and only 1 or 2 have been really close to accurate. Every other tank has been off with the computer on the high side, usually 1-2 mpg.

I will go a few tanks without resetting it and see how well it works. I usually reset it every time I fill up.