Fuel Consumption

[ROBERT]

Has anyone compared true fuel consumption (that is calculating actual fuel used against distance travelled) against what the cars readout says? My CL9 is the standard, so no readout. I suspect the cars readout would be optimistic.

[Kevl]

Has anyone compared true fuel consumption (that is calculating actual fuel used against distance travelled) against what the cars readout says? My CL9 is the standard, so no readout. I suspect the cars readout would be optimistic.

Have not done that before (because I never fill up the car) but remember reading in a review that it was a bit optimistic (like on most cars)