One of the car mags recently ran an article concerning odos and speedos. They reported that German regs dictate that speedo error MUST be on the high side, and can be within a certin allowance. However, it also mentioned that late model cars have no connection between their odo and speedo. The odo must be highly accurate, and it's error is not a function of the speedo error.
1998 C230 "Black Betty"