I have observed recently that my Suzuki Khyber 1998 model is showing wrong speed while car's actual speed is not that.
While the car is below 60 speed the difference is of 5 to 10 km/hr which means if car is actually running 30 or 35 the meter would show 40.
But when car reaches 80 the meter shows 100 and so on so in speed it is showing 20 km/hr difference.