how accurate is the MPG average display?

[nrg220]

I have a W204 C Class Sept 57. I've seen a thread on here somewhere but couldn't find it.

Just how accurate is the mpg read out on a Mercedes, I guess they would be about the same accuracy on each model.

If its reading an average of 50 mpg what is that actually. Never got around to check top up to top up.

Anyone know for sure please? Thanks and Happy New Year

 

[wemorgan]

repost?

http://www.mbclub.co.uk/forums/electronics/183894-how-accurate-mercedes-mpg-display.html

 

[geraldrobins]

Mine is 5% optimistic and that's over 1 year 16000 miles.

When it shows 52.3 its been about 2 % over, but showing 56.5 for the whole year the actual is about 53.5. I suspect the readings of up to 60 and over are more that 5% out.