For those members who've taken the time to check, what % was your fuel computer off? I'd say + or - but I seriously doubt the computer showed more MPG than doing it the old fashioned way.

My question is by how much!

My old '04 Jeep Grand Cherokee was about 1 MPG off from what the fuel computer said.

I usually got 23 MPG highway, it said 24 MPG. So it was fairly close.

My Crown Vic is about 3 MPG off. It will say I'm getting 24 MPG highway but I'll be getting 21 MPG.

Most of what I have seen they usually say that you are getting better than what you are.


ARman

Huh, never thought to check. Then again, the car that has it averages 16 MPG so you could say I'm indifferent to fuel economy. I know, about as helpful as a DMV clerk...

I would guess the more consistent your driving and commute is, the more accurate it will be.

My Corolla is stupid accurate.

My Ford Expedition 2008 is about 99% accurate.

I have never paid attention, never looked, never calculated.
I just pull on in the closest Shell when I am getting close to a quarter tank or Sunday night no matter how much it needs so my wife has a full tank for taking the kiddos to school.
I just slide the card and be done. I don't even bother looking at the price. I do get my receipt just in case I get bad fuel.

I've never calculated the per centage, but I do know the Corolla and the Yamaha are decidedly optimistic.

And I'm anal about keeping records of fill-ups and mileage.

I bought a 275 hp SUV without worrying about the mileage and I still don't. I've never looked at the computer readout and I fill up at a half a tank unless on a road trip.

Jim

They would have to have two flow meters with one for the input and one for the flow back to the tank. So the accuracy of the meters would be in question and also don't forget the odometer and your size of tires.

How many people check their odometer reading? I have found that they can be off as much as 2 to 3 percent just with factory tires.

2015 VW Gold TDI was 1.5 miles off at 500 miles, when compared to GPS highway miles traveled.

2015 BMW R1200R is 1 mile off at 250 highway miles traveled via GPS.

2013 Nissian Pathfinder is 3-4 MPG pessimistic reads 19.2 and gets 22 to 23 MPG. I check it against mileage every fill. And GPS seems to be right on for mileage so odometer and speedometer are right on.

2012 Ford fusion. Pretty darn accurate. I stopped checking after first few months it was so close.

My Trax (shopping cart with tiny turbo motor) is off by about 3 MPG
My BMW S1000XR is dead on MPG but 2 MPH slow on the speedo Vs GPS.