3 ms·

> In fact, most cars lie to you about the speed - reporting a speed slightly faster than reality. It's a cover-your-ass measure for the car manufacturers becaus

> In fact, most cars lie to you about the speed - reporting a speed slightly faster than reality. It's a cover-your-ass measure for the car manufacturers because it's illegal to sell a car (in the US, at least) where the speedometer is inaccurate in the other direction, that is, reading slower than actual speed. Haven't seen that in a long time. Everything I've driven in recent years has a speedometer speed that matches roadside speed sign speed within 1 MPH.

20after4 2y ago
Oh for sure they are not far off, but they always round up to be safe.
urban_winter 2y ago
My 5-year-old Volvo reports 73-74 mph when GPS tells me that I'm exactly at 70mph. Similarly 21 mph when GPS says 20.
- dheera 2y ago
  If the law set the speed limit as the hard boundary, with hard punishments for driving at 70, everyone else would drive at 65, occasionally getting close to 68-69. If the reasonable speed for a road is 70, the legal hard limit could be at 75 to be considerate of this effect. But make 75 the actual hard limit with $200 fines for hitting 75, $1000 fines for hitting 80, and jail time for hitting 85. Make it almost certain to be caught if you hit these hard limits. I guarantee you fewer people would die on the roads if this is the way things worked.
kuratkull 2y ago
My experience from all the cars i have driven is that GPS shows 3-5km/h less than the car does. (In Europe)
- Cthulhu_ 2y ago
  That's actually a legal requirement (had to google some to get the source): [0]. And a graph: [1] [0] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:42010X0513(03) https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:42... [1] https://www.reddit.com/r/dataisbeautiful/comments/16mquqv/speedometer_vs_actual_speed_according_to_eu/ https://www.reddit.com/r/dataisbeautiful/comments/16mquqv/sp...
  - kuratkull 2y ago
    The graph seems a bit too much. It says that GPS 110 means ~125 on the odo. Although from personal experience I'd say it's more around a delta of 5 at those speeds, and 3 for lower speeds.
    - detaro 2y ago
      it has to fall somewhere in the shaded area. So if it shows 125, then the actual speed must be between 125 and 110 at worst.

20after4 2y ago

Oh for sure they are not far off, but they always round up to be safe.

urban_winter 2y ago

My 5-year-old Volvo reports 73-74 mph when GPS tells me that I'm exactly at 70mph. Similarly 21 mph when GPS says 20.

dheera 2y ago
If the law set the speed limit as the hard boundary, with hard punishments for driving at 70, everyone else would drive at 65, occasionally getting close to 68-69. If the reasonable speed for a road is 70, the legal hard limit could be at 75 to be considerate of this effect. But make 75 the actual hard limit with $200 fines for hitting 75, $1000 fines for hitting 80, and jail time for hitting 85. Make it almost certain to be caught if you hit these hard limits. I guarantee you fewer people would die on the roads if this is the way things worked.

kuratkull 2y ago

My experience from all the cars i have driven is that GPS shows 3-5km/h less than the car does. (In Europe)

Cthulhu_ 2y ago
That's actually a legal requirement (had to google some to get the source): [0]. And a graph: [1] [0] https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:42010X0513(03) https://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:42... [1] https://www.reddit.com/r/dataisbeautiful/comments/16mquqv/speedometer_vs_actual_speed_according_to_eu/ https://www.reddit.com/r/dataisbeautiful/comments/16mquqv/sp...
- kuratkull 2y ago
  The graph seems a bit too much. It says that GPS 110 means ~125 on the odo. Although from personal experience I'd say it's more around a delta of 5 at those speeds, and 3 for lower speeds.
  - detaro 2y ago
    it has to fall somewhere in the shaded area. So if it shows 125, then the actual speed must be between 125 and 110 at worst.