Outback Calulates MPG Higher than Feully

[coxch1]

The average MPG reported by my 07 Outback on its handy-dandy little display is typically about 1-1.5 MPG better than what is calculated on Feully.com. Anyone else have the same experience?

[DTMAce]

Not with an Outback, but with my old caravan it had a MPG calculator. It also didn't match, and even if I simply did the math myself it didn't match. The one on the vehicle is usually an approximation.

The true MPG is revealed over time as you use the vehicle. Plus with the vehicle one, often I would reset it when I did an oil change, to see if it would affect it more during each oil change, and it would. Winter would show lower MPG and Summer higher, but neither would exactly match Fuelly or my own calculations.

Hope it helps.

[Draigflag]

Car's computers are just for guidance, even your speedometer will be up to 10% inaccurate! My car's MPG calculator is typically 2 to 3 MPG's higher than "actual" MPG's but you have to brim the tank every time to get accurate data.

[Ciderbarrel]

Putting on wrong sized tires w/o adjusting your on board computer will result in an incorrect speedo.

[DTMAce]

That assumes that all cars have configurable computers, and that he actually has smaller or larger tires mounted on the car.

There are many cars out there (mostly older years) that cannot be adjusted for tire sizes, or that don't even have a computer in them don't forget.

[HTWB]

I ran a 2500cc Outback automatic over about 14000 miles. The display usually averaged about 15% above the true mpg. There didn't seem to be any easy way of adjusting it. Tyres etc were all standard.

[Codyroo]

I see about a 5 - 6% high reading on my Prius displayed MPG. The MPG you get by calculating the miles divided by gallons (as done by fuelly) will be more accurate over time. Most car displayed MPG's are overly "optimistic", but it gives you a ballpark number.

[GrievousAngel]

Why do you have to "brim your tank?" If you use odometer readings and actual gallons, won't this come out accurate over time?

[MMUK]

Over time, yes, but if you want to get the most consistent measurement possible for an individual them always-brimming&venting is more accurate than just filling to the first-click. Pumps can vary significantly as far as the first-click is concerned.

[beland]

The difference between the MPG display in my '07 Elantra (28.9) and Fuelly average MPG (28.8) is only .01 — unbelievably close.