The Great Speedometer Debate


How Fast Are You Really Going?

With traffic about to pick up again following the end of half term and working professionals getting back on the road, you may have noticed the difference in speed between your sat nav and the speedometer in your car. But which one should you follow?Speedometer and Satnav

Sat Nav vs Speedometer

We're all aware of the various speed limits that are enforceable on our roads and, in the majority of cases, we stick to them. But, you may have noticed that when you use your sat nav, in comparison to your car's speedometer, the speed can be at least 3-5 mph in difference.

Typically, your sat nav will read a different speed to your car's speedometer making it difficult to know which one is displaying your true speed and at what speed you should really be driving at on the roads.

Your sat nav and your car's speedometer calculate speed in two different ways. This is one of the obstacles to getting an accurate reading of your speed on the road. This can become a problem if you are using your sat nav to calculate your speed instead of your speedometer.

The speedometer measures your speed by the continuous turns of a driveshaft, the wheel or gearbox. Your car will then relate this to the rolling circumference of your car's tyres to give you the road speed. Sat navs calculate your speed by constantly updating your location by using GPS with their accuracy being at their highest when on a straight, level road.

Nowadays, your sat nav is likely to be more accurate than your car's speedometer, but this doesn't mean that you should rely on it for your day-to-day driving. Your car's speedometer will never understate your speed, so if your car says you are travelling at 30mph but your sat nav says 27mph, don't speed up to match your car with your sat nav.

A Huge Price to Pay for Speeding

There are various types of speed cameras used on the roads and motorways and sat navs were not made to be speed indicators so using them to judge your speed on the roads can be misleading. It is much better to stick to the speedometer in your car.

The minimum penalty for speeding is 3 points on your licence and a fine of £100 assuming that your case is dealt with by the fixed penalty system. However depending on the actual speed you exceeded the limit by, the consequences can be much more severe and could result in your driving licence being endorsed with up to 6 penalty points or a disqualification in the alternative.

The added danger with speeding is that it could become a totting up offence. This means that if you have built up 12 points or more in a 3 year period you will be disqualified from driving for a minimum 6 month period unless exceptional hardship can be argued.

Something as simple as misjudging your speed using a sat nav could cause you to lose your licence. If you find yourself prosecuted for speeding early legal advice is essential. People that use a motoring solicitor are more successful in keeping their licence and staying on the road than those who don't.

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