accuracy of mpg gauges in newer cars?

[hi tech hillbilly]

out of curiosity, we have a 2005 explorer with the 4.0 v6 engine and it returns pretty god mpg on the interstate for such a big vehicle!! i work about 50miles away from my house and i was driving this beast 5 days a week for about a month and getting a 2 way average of about 26.5mpg on low wind days according to the factory fuel computer. granted this drastically decreases with crosswinds (we average about 3-4 days a week with a stiff westerly crosswind from 10-35mph), but this has me intrigued.. the trip back always yields the highest mileage (between 28-35mpg) given it decreases in elevation by about 1500 feet between indian springs and las vegas. i havent seen anything about cylinder deactivation on this truck, and it seems too good to be true, but i was getting about 6 round trips use on a tank before i had to fill up. i would say thats pretty good for a mid sized suv!!

nate sanders

[Jay2TheRescue]

If you're going downhill you got 2 things going for you... Less throttle is needed to maintain speed, and the vehicle may also be entering DFCO mode, and actually running for short periods on vehicle momentum using no fuel.

-Jay

[theholycow]

You should really verify it by calculating your fuel economy at fillup. Each time you fill, reset your trip odometer. Note what it was before you reset it. Divide that number by the gallons you put in. Compare that to the tank average provided by the computer.

You can also feed miles and gallons into a gaslog on this site and let it do the math (as well as providing a nice graph to show you trends).

[hi tech hillbilly]

im not currently driving it now, im driving a 99 camry 4 banger so i will be entering the info for it now.. the explorer is not getting driven much currently, and i leave it for the wife since i drive 100+ miles per day..and who am i kidding, that hulking behemoth aint getting better mpg than a 4 cylinder toyota..lol..

nate sanders

[Mike T]

The OBC in my Mercedes B 200 is about 6% optimistic, same as other Benzes I've driven. So I would say that they tend to be a bit rosy. The same is true of the HCHII we have at work.