XC90 D5 fuel economy is impressive

[Lexman8]

Originally Posted by Lexman8

The driving journal records fuel use to 1 decimal place so is probably reasonably accurate only on long trips.

Looking at a (mostly motorway) trip I made last night it would appear that the calculation for mpg uses a more accurate figure for fuel consumption than is displayed. It says I used 0.4 of a gallon to travel 22.6 miles which would equate to 56.5 mpg whereas it shows it as 45.3 mpg which seems about right.

I checked a few other trips and there's a similar disparity with the shown mpg always less than what a manual calculation would suggest using the displayed fuel consumption.
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[KNVXC90]

Some recent trips with good mpg figures

[S60Chris]

I’m also getting in the 40’s on a run. 2017 d5 with Polestar. I’m happy with this and suspect I could get 50mpg if I stuck to 55-60mph if i wanted to!

Adaptive cruise kills the fuel economy though I have noticed.

[Quacker]

Originally Posted by Lexman8

Looking at a (mostly motorway) trip I made last night it would appear that the calculation for mpg uses a more accurate figure for fuel consumption than is displayed. It says I used 0.4 of a gallon to travel 22.6 miles which would equate to 56.5 mpg whereas it shows it as 45.3 mpg which seems about right.

I checked a few other trips and there's a similar disparity with the shown mpg always less than what a manual calculation would suggest using the displayed fuel consumption.
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On all cars that have had a MPG calculator that I've owned over the last ten years, they have been least accurate on short journeys.

I've tested my XC90's readout, the TM one, over longer distances adding up to near 500 miles in total, but no individual journey in the total of less than 35 miles, and was amazed that there was less than 0.5mpg disparity with the fuel pump and milage calculation done manually. The 07 Audi Q7 was up to 1.5mpg optimistic.

[KNVXC90]

And finally the magic figure 52.9 mpg!

This was on a trip with a mixture of 20, 30, 50 and 70 mph roads. In Eco mode with a bit of conscious driving, anticipating my stops, and avoiding harsh acceleration where possible.