Speedometer Accuracy.

Discussion in 'Hyundai Kona Electric' started by Kitsilano, Apr 13, 2019.

To remove this ad click here.

  1. Kitsilano

    Kitsilano Active Member

    Speedometers usually show speeds higher than the actual speed. European law ECE-R39 says speedos cannot show less than the actual speed AND they must never show more than 110 per cent of the actual speed plus 4 km/h. This means that the speedometer in a car going 100 km/h could legally show a speed as high as 114 km/h. But what rule do Hyundai engineers follow? Do they follow "Electric Speedometer Specifications J1226" set out by the [U.S.] Society of Automotive Engineers? It states that above 55 mph [or 88 km/h] the allowable range for speed is 4 per cent of the highest reading on the speedometer. This would mean that a speedometer on a Kona Electric going 100 km/h could legally show a speed as high as 108 km/h on its speedometer (which goes to 200 km/h).

    Testing my own Kona's speedometer by comparing it with simultaneous speed-readings of a high-quality Garmin GPS, I find that my Kona's speedo is reporting 44 km/h at 40 actual; 62 km/h at 60 actual; and when showing 80 or higher speeds it is dead accurate! I never saw such accuracy in the string of BMWs I have owned over 3 decades. Mind you, you may not get this amazing accuracy if your car is shod with (the standard) Nexens. As soon as I could, I replaced the Nexens with Nokian WRG4 All Weather tires of the same (apparent) size inflated at the standard 36 pounds p.s.i. I have driven my car 4,000 km.

    Factors that can change speedometer accuracy are tire wear, tire inflation, and even change of replacement tires of the same size. I suspect that 'new car' Nexens are slightly smaller than my Nokians. The only way to test this is for someone else to try the same experiment with a reliable GPS and Nexen tires.
     
    CJC likes this.
  2. To remove this ad click here.

  3. Mine is 3 - 4 km/h over at all speeds up to 100 km/h. Standard tires and 5,500 km on it.
     
  4. Kitsilano

    Kitsilano Active Member

    Thanks for the report from NZ. By "standard tires" do you mean Nexen tires?
     

Share This Page