Originally Posted by Trouble65
That's the only way to measure your fuel economy.
IMO yes..people rely on the OBC but it's definitely not as accurate, at least in a way we want it to be..
Example: I reset the fuel economy and drive 200km on the highway and it'll show 15.5l/100km, then I take an exit and drive 100km in the city and the economy will show 17.0l/100km. If I reset the fuel economy when I got off the highway after 100km in the city OBC would be showing me 22l/100km
It goes by an average economy for the last 500-700km so it takes a while for it to change..