I´ve had mine since Sept 2011. According to my GPS the speed is .8 times the display. 20 displayed = 16 real, 40 = 32, 60 = 48, etc. I´ve had it up to 80 displayed (64 real). Love this scooter! 550+ miles on the odometer (440+ for real). The .8 affects the odometer, too. Probably the same electronics and drive train as the E-Charm 150 which has 16 inch wheels - the Glory has 14 inch wheels. I think that would account for the .8 factor.