I reset my mileage computer to wipe the memory and found the mpg shown improved considerably. On the M25 at a steady 60 it was showing 60mpg. I have never achieved that in the 18 months I have owned it. The roomie is a 63 plate 1.2tsi 86bhp.

Edward

Irrespective of what figures you are getting on the display the only true way of knowing your mpg is to do a brim to brim fill check.

Yes MFA is usually 10-15% out

I normally reset the MFA every time I fill up

 

I found the MFA on the GLII was about 8% optimistic, never seen one under estimate, as that would not look good for customers to think their chariot was doing less MPG

 

call me cynical but I think this is why all manufacturers seem to make the trip computers over estimate the MPG

 

is this how they get the unreal MPG figures in the brochure

No the unreal figures in brochures come from either a rolling road with just enough fuel in the vehicle

Or I believe there is a certain circuit I'm down that has optimum conditions for higher mpg than you and I will ever get but I think that's also used for the EU emissions