Speedometer off

[jackr1s]

Is everyone’s speedometer off by 2 miles an hour, when going over 50? Says you’re going faster than you are.

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[Taco]

47 = 45

2022 R1T

 

[UnsungZero_OldTimeAdMan]

This again? It’s normal and common among all cars. It’s better for OEMs to report higher than actual, than to report slower than actual and be out of compliance with regulations. Been like this for decades. Consumers became aware when consumer grade gps devices became available.

 

[Shaqdeez]

The real question is, are miles on the vehicle more than we're actually driving?

 

[McLovin]

This again? It’s normal and common among all cars. It’s better for OEMs to report higher than actual, than to report slower than actual and be out of compliance with regulations. Been like this for decades. Consumers became aware when consumer grade gps devices became available.

Yeah, assuming the phone's GPS is more accurate, my wife's A5 reports 2-3 MPH faster than the GPS speed shown in Google Maps (via CarPlay).

 

[Golfer04]

Is everyone’s speedometer off by 2 miles an hour, when going over 50? Says you’re going faster than you are.

Unless something has changed (which it could have) odometer is based on tire rotations and based on tire circumference when new. So odometer is always off depending on tire wear. At least that is the way it used to be.

 

[mudito]

BTW, am I the only one who accounts for this when setting cruise control? If I want to drive the speed limit (I always do ) and it's posted at 75mph, I set my cruise control at 76mph...

Please tell me that I'm not the only crazy dude who does that.

 

[Laserboy1054]

This is completely normal: there are regs that make a manufacturer liable if a driver exceeds speed limits due to a defect in the spedometer. Since any measurement instrument will have inevitable systematic errors, manufacfurers intentionally tune spedometers to read high. That way, any spedometer systematic error will still result in the vehicle's actual speed being below the posted limit.

There are historical analogs to this. E.g., the "baker's dozen" originated in an era in which there were severe penalties for selling bread that was underweight. By giving the customer an extra roll (or whatever) everyone can be comfortable that any systematic error in the weight of each roll is over-compensated for by the additional roll. And the baker gets a happy customer who walks away thinking he has received some special largesse.

In the case of motor vehicles, the odometer operates separately from the spedometer. So the detuning of the spedometer does not result in a flawed odometer reading.

 

[Dave Cundiff]

Washington State's interstate mileposts, when consistent, seem to be pretty accurate. (For statisticians: there are some big inconsistencies in a few spots, but not much systematic bias.)

Based on this standard Our 2023 R1S reads about 0.4% above actual speed. Our 2023 R1T reads about 0.4% below actual speed.

This MIGHT be a little more accurate than our 2019-2023 Bolts. It is much more accurate than our 2017-2018 Kias, both of which used to read about 2.2% below actual speed.

With our Rivians, our tire variations may be more important than any vehicle-related inaccuracies.

Best to all!

 

[R1Thor]

This again? It’s normal and common among all cars. It’s better for OEMs to report higher than actual, than to report slower than actual and be out of compliance with regulations. Been like this for decades. Consumers became aware when consumer grade gps devices became available.

Yeah, well.. just shows what YOU know.

My Mazda Rental shows 1 mile LESS than I'm actually travelling (based on GPS data). When I set the Cruise to 75, I'm actually doing 76. So...there!

/sarcasm

 

[UnsungZero_OldTimeAdMan]

Odometers are accurate. Not tied to speedometer. A simple web search would have delivered answers on both.

And consumer GPS is not as accurate as what the military has.

 

[Grognard79]

BTW, am I the only one who accounts for this when setting cruise control? If I want to drive the speed limit (I always do ) and it's posted at 75mph, I set my cruise control at 76mph...

Please tell me that I'm not the only crazy dude who does that.

I do this too. My speedo is also 1 MPH fast. It really bugs me, especially since my old RAM truck was dead on. I asked Rivian service about it and they said it's within tolerance, so they won't do anything about it.

 

[mudito]

I do this too. My speedo is also 1 MPH fast. It really bugs me, especially since my old RAM truck was dead on. I asked Rivian service about it and they said it's within tolerance, so they won't do anything about it.

My Focus RS is 100% dead-on with GPS as well. I wish there is an option in the menu to accept liability, like a "I pinky promise that if I get caught speeding is 100% my fault, show me accurate Speed pretty please" toggle.

 

[f1racer328]

Comparing an iPad/iPhone GPS with an airplane GPS (737, E175) I can assure you the GPS speeds on phones are accurate under good conditions (Good view of the open sky, not driving around in a city full of skyscrapers)

I really haven't bothered checking my Rivians speedometer accuracy, but I do know it is evenly matched with my other vehicles.

 

[UnsungZero_OldTimeAdMan]

Comparing an iPad/iPhone GPS with an airplane GPS (737, E175) I can assure you the GPS speeds on phones are accurate under good conditions (Good view of the open sky, not driving around in a city full of skyscrapers)

And this is the difference between consumer-grade and military-grade GPS. Clear sky vs all-conditions.

A couple of mph off isn't a big deal, especially once you are aware of the deviation. Arguing against a police officer, in court, of his laser gun's reading is rarely successful anyway.

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