Wildly Optimistic

[Marquisofraspberry]

The computer based fuel consumption on my C270 cdi. I always fill up to the top and note the mileage which then gets added to a fuel tracking site called fuelly.com . For an example the last fill up the car said 51.7 when it was actually 43.7 is there a hidden menu where you can adjust the wayward computer? It's a 2002 model.
On later BMW's there is a hidden menu option of correction factor where you can do such an adjustment.

 

[daveenty]

I've usually found the Mercedes read out to be something like acceptable to be honest, as far as I'm aware there is no way of adjusting it.

I'm assuming that you have the correct factory wheels and tyres and that you have the settings on fuelly in UK (Litres, Miles, UK MPG), and not the US (Gallons, Miles, MPG) which it defaults to?

 

[Deletedmember130310]

when was the car computer last reset ,relative to the refilling the tank?

If the computer is calculating over say 1000 miles but the app is only over, say, 200 miles, the results could be quite different

 

[Marquisofraspberry]

I've usually found the Mercedes read out to be something like acceptable to be honest, as far as I'm aware there is no way of adjusting it.

I'm assuming that you have the correct factory wheels and tyres and that you have the settings on fuelly in UK (Litres, Miles, UK MPG), and not the US (Gallons, Miles, MPG) which it defaults to?

standard wheels and correct fuelly settings

 

[Marquisofraspberry]

when was the car computer last reset ,relative to the refilling the tank?

If the computer is calculating over say 1000 miles but the app is only over, say, 200 miles, the results could be quite different

reset the computer at every fill up and generally it's nearly empty on fill up so 55 litres plus each time.