I think the Japanese have a knack for engineering their speedometers to read 10% over the actual speed
Eg at 30 mph you will be doing 27/28 mph, 40 would be 36, 70 would be 63, 80 would be 72
European ones are more likely to be 3 mph over eg 70 would be 67, 80 would be 77.
Hope this helps