how reliable is the speed reading on a tom tom one?

[vx220]

i guess more reliable than the car speedo?

[droopsnoot]

At a steady speed, it will be more accurate than the car speedo, under hard acceleration or braking you will probably find that the speed display lags behind your actual speed.

[JWB]

Do a search, this topic has been covered......

I have had 2 TTones and they gave exactly the same speed as my digital speedo that I accuratly programmed.

A friends Audi A3 speedo overead by 6mph (at 80mph) compared to the TTone. I was surprised that the speedo was that innacurate.

[vx220]

cheers guys

[robwales]

Speedos cannot under-read by law, so manufacturers set them to over read.
In my car, 60mph speedo = 57mph real, 75mph speedo = 71mph real.