Mpg Readout

[mikej]

On my dash clocks i have a little red area in the centre that tells me all sorts of info regarding distance travelled, average speed and average MPG etc, can anyone shed some light on how the average mpg is calculated or how realistic this figure shown is? it does vary with speed and has always averaged around 36 mpg on petrol and on a run but lately due to an infestation of speed cameras on the M4 i have been stuck at 50MPH for some distance and using the cruise i have seen this figure jump to 40 MPG ;) which i though a little hard to swollow.

[big_kev]

40 mpg for a petrol at 50mph is possible but does seem a bit high, I would have thought this would be dragged down on any urban parts of the route.

 

36 mpg is very unlikely if you have been doing 70mph though.

 

Only way to be sure is to brim the tank with petrol , use it and then brim it again and work out what you actually used.