I'm not worrying storeman simply wondering. I'm not looking for a complete MPG evaluation of the car, I'm just after the MPG of a particular journey and 7 miles is fine for that. As for the formula's been different there is onIy one- miles done divided by fuel used.7.5 miles is nowhere near enough to get a reliable MPG figure. It needs to use a few gallons not 0.2 of a gallon. Over time the reading will get close to a real world number. Worrying about a discrepancy on such a short journey is pointless. As for the discrepancy - who's to say the formula in the app is the same as the formula in the trip computer ?
I agree that the app has to be using different data, but as it gets the data from the car I don't know why that is. The app varies a lot with the MPG data where as the car is more consistent, so I guess it's a problem with the app.If they give different values, they self-evidently are using different data. My guess is that the app is using data averaged over a longer time period. It shouldn't do that if you operated the app correctly, so if that's the case it's probably a coding fault.As for the formula's been different there is onIy one- miles done divided by fuel used.