I’ve added the fuel range remaining to my dashboard, but its completely inaccurate – shows some 360klms remaining when the fuel light is on and less than 50klms remaining.
I did notice in the displays menu the ability to zero it. But what would be the correct sequence to get it back into sync? Do I have to literally run out of petrol and then zero it?

Additionally, the average fuel consumption doesn’t seems to change much even if I take a long freeway drive with cruise control on where I would expect it to drop and then over a weeks driving short hops around home I would expect it to rise significantly.
It seems to only wander between 11.2 and 11.6 liters/100klms and hardly changes at all.

BMW 2003 E39 – 530i auto s/wagon.
The cars own computer was removed when I replaced it with an Eonon unit giving me handsfree, navigation, entertainment and Android apps (Torque Pro).