XC70: General Trip mileage reading

[yostumpy]

I've been clearing my trip and mpg every time I fill up, but last couple of times (because the fuel pump auto shut off......didn't and it flowed out the filler cap, then next reading was spurious due to the extra fuel in there), so i have let it run on now (the mpg reading), and its currently on 47.3mpg. Question is if I don't clear this, does it keep working out the avg 'for ever' ie 100k, or for the ...say... the last 2k or 5k? surely there is only so much info the trip can store?

[Kev0607]

I think its best practice to reset it after you fuel up.

If you leave it as is, I find it just sits there & doesn’t really do anything, or takes a long time to actually update.

Average mpg readouts aren’t particularly accurate. Take what you see with a pinch of salt.

[yostumpy]

The reason it takes longer to update, or , just sits there, is the more miles that are averaged, the less impact any particular journey has, as it’s an increasingly smaller % of the total. Regarding accuracy, as I have stated before, mine is approx. 1 mpg out , as an average, per tankful, so a ‘reading’ of 47.3 would equate to an ‘actual’ of around 46 / 46.1 mpg, according to Fuelly, on a ‘fill up to click’ basis.

My question really was does the mpg readout collect and work out avg mpg , since the time it was last cleared, or the last 2000 miles, or 5000 miles etc. Don’t suppose it matters really, just thought someone might know.

[Kev0607]

Originally Posted by yostumpy

The reason it takes longer to update, or , just sits there, is the more miles that are averaged, the less impact any particular journey has, as it’s an increasingly smaller % of the total. Regarding accuracy, as I have stated before, mine is approx. 1 mpg out , as an average, per tankful, so a ‘reading’ of 47.3 would equate to an ‘actual’ of around 46 / 46.1 mpg, according to Fuelly, on a ‘fill up to click’ basis.

My question really was does the mpg readout collect and work out avg mpg , since the time it was last cleared, or the last 2000 miles, or 5000 miles etc. Don’t suppose it matters really, just thought someone might know.

I’m not sure. Maybe someone else does & chips in soon.

[apersson850]

The average consumption in the main instrument goes back to last time it was reset. This can be kept up forever. The car only needs to store the mileage at the last reset (to compute driven distance) and accumulate the fuel used since then. So only two stored values needed, regardless of how long you drive.

The average consumption shown in the secondary trip computer in the center display does the same, but can be configured to reset automatically on each new journey (defined as car hasn't been used for at least four hours).

The expected range shown in the main instrument is based on your current fuel level and average consumption the last 30 km.

The current fuel consumption shown is the average the last second, or something similar.