"Tom Korth" > wrote in message
...
>
> "pete" > wrote in message
> ...
>>
>> Mine does 21.5 according to the computer and I have never done better
>> than 21.9 which is a begger because when I picked it up it was showing
>> 22.5;-)
>> pete
>
> Don't know about the 5 series, but the fuel consumption OBC readings in my
> E46 & Z4 are 6% to 9% high. Roadspeed seems to be spot on, though.

Two E39's that both had an optimistic speedometer (by BMW design as it turns
out, to comply with German law) giving almost exactly 75mph @ 80mph
indicated. The earlier car's OBC speed was dead on, the current one is
identical to the instrument panel (i.e.: identical error). I felt I could
trust the older car's odometer ... not so sure now although I guess I could
try an extended calibration run against mile markers. The MPG reading is
usually a bit optimistic (29.0 is really closer to 28.7 or 28.8 ... between
1 and 2 %). There's a way of tweaking that in the OBC service menu, but I'm
reluctant to mess around there (although perhaps when under warrantee is the
precise time to do so).

R / John