I’ve just had a week away and done 872 miles and the computer says 27mpg.

I think that’s pretty good until I totted up the amount of fuel I’d put in. I topped up before I started and again on return. The total was 180 litres which represents 22mpg!

So is the computer wrong or is it the pumps?

It’s not the pumps!

mine is consistently giving me results approx 2mpg more frugal than in real life First time FFRR owner

If you use an app (Road Trip etc) to get the true mpg it is always 3 to 4 mpg under what the car tells you.

So my car tells me I average 35mpg but the true amount on the app is averaging 31.75mpg with the MHEV300. Still pretty good for a 2.5 tonne car and anyway you don't buy a FFRR for fuel economy do you?  All LR cars from 1984
2021.5 Vogue SE D300 Carpathian Grey
2018 Vogue SE British Racing Green GONE

My 2018 SDV8 was 6% optimistic which is double my Porsche and my wife's Golf R is only 0.4% out. It averaged 29.0 over 39k miles, which the computer thought was 30.8, so not too bad and both were better than I was expecting.

Fuel cost is a drop in the ocean compared to depreciation so I don't worry about it at all, even when I did 30k miles a year in a 750i BMW. I do like to keep a record though, always have.... MY23 Panamera E-Hybrid
MY19 SDV8 Autobiography - Sold