how does computer measure fuel consumption?

obviously its somewhat directly relatd to fuel being metered to the injection unit since it tells me 100 mpg coasting downhill and 20 mpg under hard acceleration


but i cant help but notice it gives me higher mpg when tank is full

tank full i can average 55-60 mpg on flat highway with cruise
tank at half im struggling to average 50 mpg in same situation

does it measure mass? volume? temperature/density of the fuel a factor?

how does computer measure fuel consumption?

optimistically


Other than that, I'm not sure. On my 2016 gasser, it will show --- when coasting in gear, indicating no fuel is being injected.

That's probably because no fuel is being injected when coasting in gear. The ecu estimates fuel consumption based on data from the sensors. It can be either optimistic or pessimistic depending on the data it is receiving. My '11 mfd was optimistic when stock and pessimistic once tuned.

seems to be optimistic, i got 400 miles from tippy top to half fuel gauge, at 420 miles it was telling me i had 320 miles of range on the bottom half of the tank. i got about 200. cant seem to be able to squeak 700 mi out of a tank like my mk4

Our computer reported that my car got 60.8 mpg on our first tank, and the actual mileage based on the amount of fuel used was 53 mpg. Still great, but not over 60.

jerryfreak said:

seems to be optimistic, i got 400 miles from tippy top to half fuel gauge, at 420 miles it was telling me i had 320 miles of range on the bottom half of the tank. i got about 200. cant seem to be able to squeak 700 mi out of a tank like my mk4

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I'm in the same boat. The fuel capacity on my mk7 is less than my mk4. 48.8mpg is where I stand so far, and unable to hit 700mi. per tank.

My best tank was at 62k miles. 12.775 gallons - 747 miles @ 58.5 mpg.
I usually fill up around 600 miles.

I suspect it measures amount of fuel commanded vs. the speed. Definitely reads optimistically.

Wow - I'm at ~25K miles (38K km), and struggle to get much more than 700km (420miles) on a tank; I haven't hit 800km even once yet, despite running ~60km with the low fuel warning light on at least a couple times.