speedo or Tom Tom which is correct.

[mbs]

Just noticed that the reading on my speedo is anything from 3 to 5 mph more than that showing on my Tom Tom. As the Tom Tom presumably calculates the mph using GPS it is more likely to be accurate. Is this a correct assumption? 5mph could be the diff between 3 points and none.

[Sarnie]

Tom Tom

 

 

IIRC the speedo over reads by upto 10%.

[mbs]

Tom Tom

 

 

IIRC the speedo over reads by upto 10%.

 

Thanks Sarnie, must learn this Netlingo, had to go onto Google to work out what IIRC meant

[Pingu2]

Both the EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers. These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied. The requirements are also that the indicated speed must never be less than the true speed.

[mbs]

Both the EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers. These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied. The requirements are also that the indicated speed must never be less than the true speed.

 

Thanks think I understand

[Sarnie]

Both the EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers. These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied. The requirements are also that the indicated speed must never be less than the true speed.

 

Thanks think I understand

 

My explanation was simpler

[GC350z]

I reset my speedo in my old Celica. When I plugged in an Apexi unit to remove the JDM speed limiter it gave a digital speed reading from the ECU that was lower then the dials. So I pulled the needle off the dial. Took the Apexi reading as accurate and shoved the needle back on when I was at a constant 100kph. This meant that while I was doing actual motorway speed, 120kph or slightly above, I shot past everyone else. I even cruised passed a marked cop car.

[Pingu2]

Both the EC Directive and the ECE Regulation lay down accuracy requirements to be applied at the time of vehicle approval for speedometers. These requirements are that the indicated speed must not be more than 10 per cent of the true speed plus 4 km/h. In production, however, a slightly different tolerance of 5 per cent plus 10 km/h is applied. The requirements are also that the indicated speed must never be less than the true speed.

 

Thanks think I understand

 

My explanation was simpler

 

.. but wrong

[Guest prescience]

I reset my speedo in my old Celica. When I plugged in an Apexi unit to remove the JDM speed limiter it gave a digital speed reading from the ECU that was lower then the dials. So I pulled the needle off the dial. Took the Apexi reading as accurate and shoved the needle back on when I was at a constant 100kph. This meant that while I was doing actual motorway speed, 120kph or slightly above, I shot past everyone else. I even cruised passed a marked cop car.

 

I suspect you didn't shove the hand back on the dial as you were passing the cop car