Vehicle Trip Computers

[denpacc]

Just curious how accurate people's trip computers are on their vehicles. On a recent trip into the US, my brother's Dodge with the 5.9 litre cummins (2005) said we were getting 5.5/100 (that's 42.3ish mpg's) on the trip computer. I hand calculated it and it was actually 10.2/100, still quite good but way off nevertheless.

For comparison, my wife's v8 4Runner was only off 1-3% when hand calculated on a few occasions. My vehicle is from an era that didn't have trip/mileage calculators.

How far off was your trip computer compared to hand calculations? What vehicle?

[Mistagin]

On my 2012 F-150 it is almost always dead on, and I do calculations for every tank of fuel.

[600twin]

I purchased a GMC Yukon in the USA last year and it is pretty much dead on. The father in laws Ecoboost is way off.

[Lefty]

My Sierra is pretty much spot on and the Fusion showed 34 on our last highway trip and calculated came to 35.

[Donkey Oatey]

2012 F150 ecoboost. It is within .5L on fuel used if no idling or warming up. Worst its been has been about 4L out at 100L fill up with using command start and idling for warm up.