US spec BMW's are coded from the factory with a default 3mph optimistic speedometer. It's 3mph across the board and not a percentage factor. Any additional error is due to variations in tire rolling radius.

It's very easy to change or eliminate the speedo fudge factor using ncs expert. Iirc, you can do up to + or- 6mph/10kph.

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2012 xDrive35d
2001 BMW X5 3.0i 5MT
and two 1987 Corvettes - Callaway Twin Turbo and Guldstrand Grand Sport 80
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