never owned a vehicle that had one that was accurrate. I think the auto industries just set those up to meet epa demands.

 

Mine is accurate. I very seldom zero the MPG unless I am going on a long highway trip. To check I divide Miles driven by MPG to get the amount of fuel to fill up. Usually withing .5 of a gallon. My garmin GPS will also give fuel used and cost of the trip if I set up the MPG city and highway and cost/gallon.

 

..........Mine is pretty well bang on............kim.......

 

Wait...you mean I may not be getting 32mpg on the highway like the overhead says?

The numbers are off, but it gives me a relative idea of what it's doing. When I see 32, I know I'm around 17. If I drop to 30, I'm somewhere between 15 and 16mpg.

But it is fun to play with people when they see my mileage and the screen and say "I don't even get that kind of mileage in my <insert car model here>"

 

I reset mine every tank and if it's not on, it's usually only off by a tenth or two. I'm running slightly oversized tires. 285/70/17

 

My speedo is almost dead on when I check it with the GPS.

My mileage avg. is about right, but my miles left is usually way off. It gives me a reading of 70 miles or so and only takes 26 gallons to top off the tank, leaving me around 10 gallons of fuel still in the tank, even though the gauge is below 1/4 and almost touching "E".....

 

Mine is almost dead on. I reset it on every fill up. I get a consistent ~18 mpg around town and ~26 mpg when I can get long trips on the highway.

But my Odometer is completely dead on the overhead. I did a reset one day and it never came off zero miles.

 

Everything we have the overhead is wrong. Our 04 jeep grandcherokee is the closest usually a mpg or 2 off. As for my truck I used that space for more useful things like my high idle mod!

 

My '01 is a few MPG off, even more so after I put the Edge attitude/juice.
I have had it tell me I am getting 25 + MPG before when I was trying to test the MPG I could get if I drive easily, no towing, low setting on the EDGE, no long idling and in the summer.
I can get 20 but the computer tells me, 25+
I just hand calculate the tanks, and leave that computer on temp and compass.

 

Try this -

http://articles.mopar1973man.com/