Well, guess I got lucky with my 5 then. Since day one the error has only been +2mph from about 25mph to any highway speed I've yet attempted (that's with a 40 series tire on a 19" rim). All verified by two different makes of smart phone and two different GPS speedometer apps. BTW it's not a "BMW thing" every make of car ever owned or driven has had this positive error built in, even before the overly strict speeding penalties came about.
Wir koennen alles. Ausser Hochdeutsch