Ever wondered why the speedometer on your vehicle is different from your speed on a navigation app?

Well, it turns out speedometres are designed to over-report your speed.

Road safety expert at the University of New South Wales Emeritus Professor Michael Regan told Gary Adshead on 6PR Mornings speedometers are set about five per cent faster than the actual speed of the car.

“They do this so there is no chance the car might be travelling at a speed that’s higher than on the dashboard,” said Professor Regan.

Press PLAY below to find out why this is integral to road safety