Speedometer or GPS

Central · 14-10-2010, 17:40

Now i know in the older cars the speedo can be off.

But how acurate is the Sat nav. If my speedo is saying 70 then my sat nav is reading 63-64.

So which one is more acurate?

SnoopZ · 14-10-2010, 18:02

I'd say the car speedo is. I'd also never use the speedo in a satnav if it records your speed incase you get pulled over for speeding!

**Chris** · 14-10-2010, 18:08

I'd rely on my sat nav any day. My sat-nav comes in consistently 9-10% under my speedo. If my speedo were over estimating my true speed by that much, I'd be getting flashed by every camera I pass.

Osem · 14-10-2010, 18:09

All car speedometers are set to read slightly higher than the actual speed to allow for a margin of error and avoid drivers unknowingly exceeding prevailing limits.

http://www.which.co.uk/cars/driving/...and-kmh-to-mph

Quote:

Most carmakers set speedometers so they show the vehicle travelling slightly faster than it actually is (up to a limit of around 10%) and other factors, such as tyre condition and the configuration of the car’s gears, can also affect accuracy.

jb66 · 14-10-2010, 18:20

GPS is accurate, speedometers are less acurate the faster you go due to them being a set percentage higher

SnoopZ · 14-10-2010, 18:34

Good info, thanks all.

**Kymmy** · 14-10-2010, 21:00

The sat nav will be the most accurate (though it does depend on the number of sats tracked..

All car speedo's are made to over-read (by no more than 10% and legally they can not under read) and also speedo's depend on the tyre, size and wear

The problem though with sat navs is that they're no legal as a speedo as they can fail in built up areas..

Madwelshman · 14-10-2010, 21:37

Sat Nav is more accurate. Mine sat nav was reading about 5% below speedo until I changed the front tyres. New tyres, slightly larger, speedo reading now accurate with satnav!