The long answer is that the automaker calibrated the car's speedometer to work with a very specific tire and wheel size. Installing a tire and wheel with a different diameter throws off all those ...

RP You’re right that GPS is usually more accurate than a speedometer. By law, manufacturers have to make sure that cars’ ...

Which is more accurate, the speed shown on a speedometer or a sat nav? On the occasions I use my smartphone as a sat nav, I get a readout of the speed of the car on the screen. It always shows a ...