I did a brim-to-brim refuel yesterday. 52 litres after 575 miles gives just over 50mpg. The dashboard figure was 54.8. So, around 8% optimistic.

I think 50mpg for a car the size of a Superb (half motorway at 70-75, quarter cross country A-roads and a quarter very short town work) is brilliant, especially as it's not a Greenline, but wondered if anyone else had worked out an error percentage for the dash mpg figures?

Stuart

Most people are finding differences of 8-10%. Mine is about 7.5% optimistic.

If it really bothers you there are threads on here that will tell you what to change using VCDS to get it to be more accurate.

No; doesn't bother me. Now I have a correction figure, I can get a more realistic sense of real mpg.

Stuart

The only time I bothered to brim it b4 and after a journey was last week, a 39 mile run out virtually all motorways and duals at speeds I dare not print, off peak and generally clear run but a good few kick downs in 37 mins, the return took over two hours and because of detours and peak traffic stop start stuff totalled 90 odd mile. Mine showed 36.7mpg against the brim to brim 37.1 mpg, not worked out the % but am well happy with accuracy and mpg considering its the CR170 Dsg and daft driver.

Edit: oops got my figures arse about face, my screen was the more optimistic figure.

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Often comes up on the Yeti forum as well!

One suggestion that has been made is that the programmers have used the conversion of 1 gallon as 5 litres and not 4.54.

If you're really bothered about mpg, all you need to know is what driving style makes it better and what style makes it worse. Absolute figures only come into it when bragging.

I can't believe I seem to opposite to the mould.

On first 3 tanks in this car, it's been about 2-3mpg LOW compared to brim to brim calcs. Therefore I don't think the calc thing is true

Yep mine read about the same, the true figures are in Fuelly

About 10% +/-1% for me - pretty much the same as my Octy. My wife's Fabia is pretty much spot on.

Often comes up on the Yeti forum as well!

One suggestion that has been made is that the programmers have used the conversion of 1 gallon as 5 litres and not 4.54.

Fiat Multipla owners found they got better consumption than indicated, the error relative to the litre figures inducating the use of US gallons rather than UK ones in the conversion software!

Stuart

If the mpg readings are slightly off, does this make the distance to empty reading also off? Presuming the Superb has that, I haven't checked.

If the mpg readings are slightly off, does this make the distance to empty reading also off? Presuming the Superb has that, I haven't checked.

... yea, but the closer to 'empty' you get, the smaller the error becomes ...

I can't believe I seem to opposite to the mould.

On first 3 tanks in this car, it's been about 2-3mpg LOW compared to brim to brim calcs. Therefore I don't think the calc thing is true

I get that with my Octy. My old Civic, however, used to read about 15% out!

You can easily correct the figure with VCDS, did it on my VRS with 107% and also on my A6 with 107%

Seems that most VAG figures are 7% too optimistic.

Since picked up the car and fill the tank at 12 miles, I then started to calculate the mpgs on a 720 miles trip, brim to brim, two fills, 67.33 Litres. So 48.5mpg.

The computer showed 51.3mpg average at that time.

So around 6% error.

Edited 31 May, 201214 yr by redbuta

I'm not filling mine up that much. But I did get 656.8 miles from 49.5 litres which works out at 60.2mpg. The OBC showed 63mpg so 5% out.

Have you guys checked the odometer accuracy?

It briefly agreed with my TomTom, also briefly agreed with the google map (trip computer shows around 10 miles longer than my pre-trip plan on the google maps, however I made a few wrong turns and once took the wrong exit on a roundabout which cost me extra 4 miles...)

Have you guys checked the odometer accuracy?

First run, mine is showing 49.1, I calc it as 43, 12% error - I thought it would overestimate a bit but margin shocked me.

Not your maths then?