Quoted MPG - how accurate is it?

[KXL]

I wonder if switching RONS (eg...sometimes put 95, sometimes 97, sometimes 99) would make the mpg gauge compared to actual mpg less consistent? Or as the car is (I'm guessing) mapped to run 95, 95 fuel gives it the most accurate real world mpg in comparison to computer read out? Oh and if you can get 600 miles out of a 45 litre tank...I will shake your hand . That's averaging 60mpg..real world.
I had a 2.0TDI that could do almost that, but it had a bigger tank and on highway it would average about 60mpg. Well that time at 550 miles the red light came on...

 

[RUM4MO]

I also tend to like to use the same pump again and again, but I've never ever intentionally continued filling until the "£" - I only do that until the complete litre or 0.5litre and record the fuel I've loaded into the tank - only once or twice newer/stranger pumps have lured me into accidentally force filling to the next complete £.

Still too much "I get a weeks driving out of £35 - is that good?" being mentioned on these VW Group and probably other forums.

I have had cars with fuel computers for 34 years now and all I've ever expected from them was to give me a reasonably accurately indication of short term and tank to tank MPG, if I ended up with a trend towards increased consumption I would quickly know about that from the short term figures I observed while driving or if I left it long enough the tank to tank figures that I was recording at refuel time.

 

[camelspyyder]

If I'm doing a brim to brim check I like to use the same pump both times as well, but I stop at the click.

 

[Imperial]

I reckon I've now topped out and can't get any more unless I was to do a long non-stop run. I got an indicated 61.3 and an actual of 56mpg. 8 miles short of 600 miles, but I did manage to get more than 45 litres in, so that's cheating. That was standard unleaded. I might again try one of the other super unleaded but I think it will be difficult to justify.

 

[KXL]

I reckon I've now topped out and can't get any more unless I was to do a long non-stop run. I got an indicated 61.3 and an actual of 56mpg. 8 miles short of 600 miles, but I did manage to get more than 45 litres in, so that's cheating. That was standard unleaded. I might again try one of the other super unleaded but I think it will be difficult to justify.

Lots of 2 cylinder fun on 40-70mph roads? Last month did London to Manchester starting at 7am, trip computer indicated 57mpg...from experience with brim to brim calculations, probably around the 56mpg mark..calculated. But if the 1.4ACT and 1.0EcoTSI did the same mpg, I'd much rather have the extra 40PS!