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Speedometer Accuracy?

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The town I live in has a few permanent speed indicator signs that show your speed and flash if you are 1 MPH over the limit. Based on what it (not very scientific by any means) says, the car indicates a speed about 1-2 MPH below what the sign typically says.
 
I'm curious, does the Model 3 user GPS to determine speed or does it do it like other vehicles and it's the rotation of the tires? If the latter, most companies err on the side of caution. IE they set it so you think you're going faster than you are.

Mine is 2 MPH faster than what I see with my phones GPS. That's 1 MPH better than the car I replaced, it was 3 higher than my phones GPS.
 
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Reactions: APotatoGod
I set up a GPS speedometer app on my phone and it reported about 1mph slower than what Model 3's speedometer reads.

Honestly, I'm quite disappointed in this. If I see a number, I expect it to be accurate. You'd think that the car would use GPS to calibrate the speedometer like my bicycle computer does.

I am assuming you have had your phone GPS recently calibrated and certified to be accurate.
I had the same thought.

Trying to figure out if the OP's posting is serious or not since the only ratings on the initial posting are "funny".
 
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Of course I'm serious. I'd fully expect the speedometer to be dead on. Anything other than that isn't telling me the info that I want.

It should be quite easy to periodically calibrate the speedometer with the GPS.

As for my phone's GPS, it's true that I just picked up an app from the app store. I'd assume it to be correct, but I should probably use my cycling GPS that has speed to the tenth.
 
Of course I'm serious. I'd fully expect the speedometer to be dead on. Anything other than that isn't telling me the info that I want.

It should be quite easy to periodically calibrate the speedometer with the GPS.

As for my phone's GPS, it's true that I just picked up an app from the app store. I'd assume it to be correct, but I should probably use my cycling GPS that has speed to the tenth.
I have a Garmin Edge 800 and have compared my speed with a cyclist riding next to me. Our speeds typically vary and are more likely to differ then be the same. I'm not saying the Tesla speed is accurate but it isn't something I worry about.
 
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Reactions: APotatoGod
Of course I'm serious. I'd fully expect the speedometer to be dead on. Anything other than that isn't telling me the info that I want.

It should be quite easy to periodically calibrate the speedometer with the GPS.

As for my phone's GPS, it's true that I just picked up an app from the app store. I'd assume it to be correct, but I should probably use my cycling GPS that has speed to the tenth.

You do know that cars do NOT have an accurate speedometer right? Unless you pay a 3rd party to tune it to 100% it's going to be off and most likely reporting higher than what it really is.
 
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You do know that cars do NOT have an accurate speedometer right? Unless you pay a 3rd party to tune it to 100% it's going to be off and most likely reporting higher than what it really is.
It’s also common practice to report faster than actual. No blame for speeding tickets. My bmw, Acura, dodge, and Tesla are all off. The Tesla is closest.
 
It’s also common practice to report faster than actual. No blame for speeding tickets. My bmw, Acura, dodge, and Tesla are all off. The Tesla is closest.
I set up a GPS speedometer app on my phone and it reported about 1mph slower than what Model 3's speedometer reads.

Honestly, I'm quite disappointed in this. If I see a number, I expect it to be accurate. You'd think that the car would use GPS to calibrate the speedometer like my bicycle computer does.

Truly an Earth shattering first world problem.
 
  • Funny
Reactions: APotatoGod and TT97
I set up a GPS speedometer app on my phone and it reported about 1mph slower than what Model 3's speedometer reads.

Honestly, I'm quite disappointed in this. If I see a number, I expect it to be accurate. You'd think that the car would use GPS to calibrate the speedometer like my bicycle computer does.

By law a speedometer can never report slower than you are really moving, but they are allowed to report up to 5% faster than you are going. As a result all speedometers read faster than you are actually going.
 
  • Informative
Reactions: APotatoGod
Of course I'm serious. I'd fully expect the speedometer to be dead on. Anything other than that isn't telling me the info that I want.

It should be quite easy to periodically calibrate the speedometer with the GPS.

As for my phone's GPS, it's true that I just picked up an app from the app store. I'd assume it to be correct, but I should probably use my cycling GPS that has speed to the tenth.
I am not sure about the US, but as far as I know in Europe there is a law that a Speedometer always has to be slightly inaccurate to make sure that people are never speeding by accident. This way they can't get a ticket if they stick to exactly the speed on their speedo.
 
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