Are UK car speedometers accurate?

Under UK law – which is based on a European Union standard – speedometers must never underreport a vehicle’s speed, while it must never overreport by more than 110\% of the actual speed + 6.25mph. So if you’re going 40mph, your speedometer may read up to 50.25mph – but it can never read less than 40mph.

Which speedometer is more accurate?

Industry officials have said speedometers are set “optimistically” to give drivers an inflated sense of speed (and help them avoid tickets). GPS devices record distance over time without the effects of mechanical variables and thus tend to be more accurate.

Are GPS speedometers legal in Canada?

Transport Canada doesn’t regulate speedometers for accuracy. Steve Wightman noticed that his speedometer readings didn’t match those of his GPS. Transport Canada doesn’t regulate speedometers for accuracy.

Why do cars have speedometers?

First and foremost, speedometers in most vehicles are designed to overestimate the speed of travel. International law has long required modern cars to overstate true speed.

What is the law for car speedometers in the UK?

The law for car speedometers in the UK. The UK law is based on the EU standard, with some minor changes. A speedo must never show less than the actual speed, and must never show more than 110\% of actual speed + 6.25mph.

Do New Zealand speedometers overstate true speed?

International law has long required modern cars to overstate true speed. The applicable standard for many vehicles sold in NZ is a European standard that specifies that speedometers must not indicate a speed less than the vehicle’s true speed, or a speed greater than the vehicle’s true speed by an amount of more than 10 percent plus 4 km/h.

Are SAE-calibrated speedometers accurate?

If you go by the formulas, SAE-calibrated speedometers will definitely be off as you cross into triple digit speeds, and European ones may still be on target. In practice though, for people that don’t constantly stare at a speedometer while driving at high rates of speed, the SAE speed is more likely to read true. What about my odometer?