Is my Tom Tom Sat Nav more accurate than speedometers?

staples_92

the tom tom isent going to give an acurate speed because it's all satelite linked and the satelights are farly slow, so id go with your speedometer

StephenWeinstein

The satelite system incorrectly assumes you go in a straight line between the points where it locates you. The speedometer (correctly) reflects that you actually go a longer distance, because of curves in the road, lane changes, etc.

the rocket

Tom ,toms are drums and their sense of direction can lead you up a blind alley.Or a bridge that is not 100% constructed.A speed ometer very seldom lies as it does not speak!.But in all fairness it can work out distance and speed.Tom Tom will instruct you to go on the railroad.Watch out!.TAKE THE NEXT LEFT.Its scary I was frightened.

UCANTCME

NO IT IS NOT.

todvango

Holy cow, I am shocked at the number of people who think their GPS is going to give them a more accurate speed.

It's getting signals from a satellite in space! It's going to take time to process and update your speed. I guarantee you if you speed up 10 MPH, your speedometer is going to register that change before the GPS unit will. Plus as you go around corners and through intersections, the GPS system is just calculating an average, the speedometer is showing speeds in real time.

The ONLY argument I could make for the case of the GPS being more accurate is over a long highway trip on mostly a straight strech of road, if the car's speedometer is actually off a bit, I think the GPS speed could wind up being the more accurate number. But again, this is just an average. If you are seeing a noticeable disparity there and you truly do think your car's speedometer is not reporting your speed properly, I'd get it checked out.

Phil McCracken

This happens with mine too. To keep within the law at speed cameras etc, trust the one fitted in the van!

Various things can affect the accuracy of the analogue speedo, such as how much your tyres are inflated. I would say the Tom Tom is likely to be more accurate, though it can take a second or two to reflect the correct speed.

kriss_plc

it has to be updated with the newest software
otherwise it doesn't even tell you when a camera approaches

SnoddersB

No. It can only give average speeds and so is not instantaneously accurate. if you are done for speeding it is no use claiming that Tom Tom gave a lower figure. Any way GPS is not that accurate.

Ring of Uranus

YES! sat navs measure your average speed over a fixed
(usually about 2 metres) distance.

Speedo's are factory set at between 5 and 10 % below potential to compensate for oversize tyre fitments and possible lawsuits from owners who are involved in accidents in which speed can be shown as a factor and the driver can show the cars speedo is responsible for the error.

The Sat Nav will register your exact speed.

Alanrt1

tom tom!!

mistress_coleen_01

Your TomTom is more accurate.

whycantigetagoodnickname

TomTom, that woman is always right, and boy do you know when you get the route wrong. Just trust her when she says you are going too fast - flee in ear? Nearly bit my head off. And she should be more accurate than normal speedo over a long distance, short term the van speedo will give you a better indication (say, over 5 seconds), and will show quicker if you are speeding up, slowing or maintaing constant speed.

compyshop

By Law, speedometers only have to be accurate to within 10% anyway, but are usually fairly good up to about 30mph..

Sat nav is far more accurate on a constant speed.

ryan

Totally agree, my saab 93 speedo reads 30 mph under and over!

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