how accurate are the Mercedes mpg 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]

In my 2013 SLK the difference between tank-to-tank mpg and the digital display is <1%

 

[nrg220]

mpg readout

Thanks, well that's not much, bit surprised but good though it if correct

 

[renault12ts]

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

Well, when you do get round to it you will know.

Yawn.

 

[artyman]

Not very in my experience

 

[Bjm34new]

Mine mile's out "MILES" get it?
last check OBC gave a reported figure of 42.6 against a brimmed tank to brimmed tank figure of 37.2.

would prefer the OBC to be correct but alas I always get around 5MPG difference between the 2 readings and never the way around I would like

 

[Red C220]

Mine mile's out "MILES" get it?
last check OBC gave a reported figure of 42.6 against a brimmed tank to brimmed tank figure of 37.2.

would prefer the OBC to be correct but alas I always get around 5MPG difference between the 2 readings and never the way around I would like

I get similar inaccuracies.

Our last car a facelift 2011 C220 CDI estate auto was around 15% out on average (OBC was 15% optimistic than actual).

Our current car is providing similar with the OBC about 10% to 15% out.

 

[daveenty]

No idea really with any of the cars, though there does seem to be a fair difference between what the display tells me v fuelly or my own spread sheet. Probably only 2 - 3mpg of a difference but there again that's a lot over a few hundred miles.

Hopefully this year (brand new) I can do some more accurate recordings and try to get the thing into single figures, or at least low teens. Another year less life to live, more fuel to burn.

 

[br0ke]

Every time my reserve fuel light comes on I find the nearest BP station and brim the tank. I make a note of the comp MPG, MPH, hours and miles travelled.
Over 180 fills now and it averages 7 mpg more optimistic than it actually is,
Closest is 3.3 out and worst was 11.2 out.
I believe it counts the pulses to the injectors and presumably calculates on speed and distance. There was some talk that it could be adjusted via star, but I wouldn't go that far.