Speedometer buffer?

[Sifrk]

At a recent maintenance appointment, I asked the service manager to check my speedometer as I have noticed it was about two miles off actual. He then tells me that it's by design as a buffer against speeding. Never heard this before. Can anyone confirm this with the 5th Gen?

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[kevinmai712]

At a recent maintenance appointment, I asked the service manager to check my speedometer as I have noticed it was about two miles off actual. He then tells me that it's by design as a buffer against speeding. Never heard this before. Can anyone confirm this with the 5th Gen?

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most vehicles isnt going to read exactly, some are 2-3 mph below the dial. But it's normal. My subaru was 4 mph off

 

[Ride S40T]

At a recent maintenance appointment, I asked the service manager to check my speedometer as I have noticed it was about two miles off actual. He then tells me that it's by design as a buffer against speeding. Never heard this before. Can anyone confirm this with the 5th Gen?

Sent from my SAMSUNG-SM-N920A using Tapatalk

Seems legit. We had a "latest tech" SUV for a while and when we set the cruise at 70, it would routinely bounce from 69-70 but never above. The speedos on the side of the road would sometimes read -1 as well.

With our 5th Limited, the cruise is so very crude. It's late to detect drag and on the crest of the hill it will sometimes briefly fling us ~2-3 mph over. Usually not a big deal, true. Unless the cruise is already set at +5 over... Maybe it's designed to counter this?

 

[1engineer]

At a recent maintenance appointment, I asked the service manager to check my speedometer as I have noticed it was about two miles off actual. He then tells me that it's by design as a buffer against speeding. Never heard this before. Can anyone confirm this with the 5th Gen?

Sent from my SAMSUNG-SM-N920A using Tapatalk

SAE standard is like +- 2% for speedometer calibration. Has nothing to do with speeding, everything to do with mechanical accuracy. In addition, on a cold morning your tire will have less of a loaded radius due to lower air pressure causes by cold temp. No matter what it's never going to perfectly match GPS all the time. That's why LEO's give you some margin. #idealgaslaws

 

[manganos]

Even police vehicles with calibrated speedos have to be checked at regular intervals to make sure they are within range. It is not uncommon for the speedo to read 1 or 2 miles an hour off then a radar unit display (Moving Radar). The other way is to put it on a dyno and calibrate.

Back when I was a trooper I've had lawyers ask to see the vehicles calibration certificate. Especially when I paced a vehicle.

 

[FrenchToasty]

SAE standard is like +- 2% for speedometer calibration. Has nothing to do with speeding, everything to do with mechanical accuracy. In addition, on a cold morning your tire will have less of a loaded radius due to lower air pressure causes by cold temp. No matter what it's never going to perfectly match GPS all the time. That's why LEO's give you some margin. #idealgaslaws

When filled with nitrogen, shouldn't have any pressure difference with the colder temps? Nitrogen is an inert gas that always is the same pressure no matter the temp.

 

[ScoMey]

At a recent maintenance appointment, I asked the service manager to check my speedometer as I have noticed it was about two miles off actual. He then tells me that it's by design as a buffer against speeding. Never heard this before. Can anyone confirm this with the 5th Gen?

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I never cease to be amazed at what comes out of the mouth's of "service managers"... :lie:

 

[Jeremy556]

When filled with nitrogen, shouldn't have any pressure difference with the colder temps? Nitrogen is an inert gas that always is the same pressure no matter the temp.

That's not true at all. Don't listen to people trying to sell you nitrogen to fill your car tires, or people gullible enough to have bought it.

https://en.wikipedia.org/wiki/Boyle%27s_law
https://en.wikipedia.org/wiki/Ideal_gas_law

 

[FrenchToasty]

That's not true at all. Don't listen to people trying to sell you nitrogen to fill your car tires, or people gullible enough to have bought it.

https://en.wikipedia.org/wiki/Boyle%27s_law
https://en.wikipedia.org/wiki/Ideal_gas_law

I was mistaken, my apologies

 

[Saker]

When filled with nitrogen, shouldn't have any pressure difference with the colder temps? Nitrogen is an inert gas that always is the same pressure no matter the temp.

That's not true at all. Don't listen to people trying to sell you nitrogen to fill your car tires, or people gullible enough to have bought it.

https://en.wikipedia.org/wiki/Boyle%27s_law
https://en.wikipedia.org/wiki/Ideal_gas_law

Haha good ol wiki. I didn't listen to anyone trying to sell me nitro to fill my tires. I use it along with compressed gasses such as r22, 404a, 410a, on a daily basis. I know what temperature does to one gas vs the other.

I'm going to drop this here, and its from "Get Nitrogen Institute"

Open the link and scroll to the bottom of the page.
Nitrogen in Tires : Information about Nitrogen Tire Inflation News, Benefits, Generator Dealers, Location Finder & More


Back on topic...

 

[1engineer]

When filled with nitrogen, shouldn't have any pressure difference with the colder temps? Nitrogen is an inert gas that always is the same pressure no matter the temp.

That's not true at all. Don't listen to people trying to sell you nitrogen to fill your car tires, or people gullible enough to have bought it.

https://en.wikipedia.org/wiki/Boyle%27s_law
https://en.wikipedia.org/wiki/Ideal_gas_law

I'm going to drop this here, and its from "Get Nitrogen Institute"

Open the link and scroll to the bottom of the page.
Nitrogen in Tires : Information about Nitrogen Tire Inflation News, Benefits, Generator Dealers, Location Finder & More


Back on topic...

Some of us have ideal gas laws burned in our brain til we die.

 

[Sifrk]

What I don't think I mentioned was he offered up that he used to drive a BMW and now a Lexus. The Lexus he claims was about two miles off, where the BMW he said was four to five miles off. Obviously, most are thinking he's just FOS.

Mine is consistently two miles off. That's unscientific testing watching speed displays and using a number of apps off the Android. In comparison, using similar speed displays and my smartphone apps, my 2005 4R was pretty close to dead on far as the speedometer. I dunno, it's not a big deal, just like to understand it a bit better is all.

 

[badhabits]

Both my 2013 and 2016 read 2 MPH high, when compared with my GPS speed reading. This was from 5 mph to 90 mph, the consistent difference of 2 mph in the readings lead me to believe that it is a planed function.

:wow:

 

[alphabeast]

SAE standard is like +- 2% for speedometer calibration. Has nothing to do with speeding, everything to do with mechanical accuracy. In addition, on a cold morning your tire will have less of a loaded radius due to lower air pressure causes by cold temp. No matter what it's never going to perfectly match GPS all the time. That's why LEO's give you some margin. #idealgaslaws

But officer.. I was compensating for my reduced loaded radius due to lower air pressure...

 

[MossJenks]

In 30 years of driving I've never owned a car that had a speedometer that was perfectly accurate at highway speeds. You're really worried about TWO MPH? Heck, my Alfa Romeo is like 8 MPH optimistic. There's got to be more than a 2 MPH difference between a brand new off-road tire and a worn-out one at 75 MPH. And different brands and models often have slightly different diameters when new. How in the world would you expect Toyota to engineer a speedometer that's perfectly accurate with all of those variables? And just what would you expect the service manager to do, start replacing speedos and cables and transmissions in the long-shot hope that some combo would be perfect? Please.

It's smart design to error on the side of reading fast. Would you rather get a ticket or drive around slightly slower than you think? Which is going to make you angrier at Toyota?

 

[Sifrk]

In 30 years of driving I've never owned a car that had a speedometer that was perfectly accurate at highway speeds. You're really worried about TWO MPH? Heck, my Alfa Romeo is like 8 MPH optimistic. There's got to be more than a 2 MPH difference between a brand new off-road tire and a worn-out one at 75 MPH. And different brands and models often have slightly different diameters when new. How in the world would you expect Toyota to engineer a speedometer that's perfectly accurate with all of those variables? And just what would you expect the service manager to do, start replacing speedos and cables and transmissions in the long-shot hope that some combo would be perfect? Please.

It's smart design to error on the side of reading fast. Would you rather get a ticket or drive around slightly slower than you think? Which is going to make you angrier at Toyota?

Whoa, whoa, whoa! Hold on! I was just asking the question. Not terribly concerned about it, haven't started picketing Toyota headquarter, not losing sleep over this. Just wanted to know if there was an explanation and if others were seeing similar discrepancies.

 

[Quentin]

Normal. My GTI read 70mph at 64mph.


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[Stangboy]

I found that after going with 285 Duratracs my speedo is almost dead on now...

 

[Ghostrider]

I never cease to be amazed at what comes out of the mouth's of "service managers"... :lie:

I think I remember a lawsuit about this (Honda?) Their speedometer were calibrated to run faster so you used up the warranty faster and used up lease mileage quicker

 

[1jzgte]

1. You rack up miles faster on your vehicle so you feel like need to get a new car sooner

2. Bumps your vehicle out of the manufacturer warranties sooner

Those are my theories