Speedometer Accuracy?

[YarisPete]

I have an 09' Yaris LB with an automatic transmission. I drive a lot and when going 55 mph (according to the speedometer) I get passed a lot. When I drive my Durango 55 mph, I pass a lot.

So I tracked it with my GPS and when the speedometer says 55 mph, the GPS says about 52/53. I wonder which is correct? My guess is that the GPS is correct or else I've suddenly begun driving like I was 90 years old!

:headbang:

[Zaphod]

Were you the 1st person to own the car? It could be that the previous owner had put on larger diameter tires, changed the speedo gear and then switched back to the smaller tires for the sale without the changing the speedo gear back.

[YarisPete]

I'm the original owner and the car is stock.

[bst82551]

I have a Yaris with stock wheels as well. I believe the problem may lie in the fact that the bare-bones stock Yaris comes with 14" wheels and every other Yaris comes with 15" wheels (or bigger). The speedometer may be calibrated for the 14" wheels.... or it could just be that Toyota set it to show higher than it is actually going to keep you from getting tickets.

I realized this anomaly a month or two after I bought my Yaris and have since corrected my speed by going approximately 5% faster than what the speed limit is (68 in a 65, 37 in a 35, etc.).

[eTiMaGo]

It seems to be a problem with most yaris (and I heard the Fit did that too). One might think it's a safety feature to get people driving slower, who knows...

[YarisPete]

I guess I was a little surprised by it. The difference is even more on my motorcycle and I suppose I'll get out and measure the Durango.

[Yaris Hilton]

It's already been posted on here that there are different speedometer drive gears for the 14" and 15" wheels. Your tires are either smaller in diameter than the ones it was calibrated for, or underinflated.

May be an issue with reading the speedometer, too. Due to the speedometer being in the center, there's parallax viewing it from normal driving position. It's meant to be viewed from straight on, meaning your head in the center between the seats. From my normal position, if I put the left edge of the speedometer on the right edge of the 55 mark, it's centered over it if I do move my head over to the center.

[Zaphod]

That's weird, mine is a 2009 LB MT with stock 15" wheels and it's always matched my GPS.

I that were mine, I'd definitely verify it with another car and if it was still off, I'd be taking it to the dealership. Who knows, the car may even have been built with the wrong speedo gear.

EDIT: what YH said, you should definitely check your tire pressure.

[bkrownd]

So I tracked it with my GPS and when the speedometer says 55 mph, the GPS says about 52/53. I wonder which is correct?

This is the way speedometers are designed. They typically read 3% or more faster than the true speed.

[GrimlockGT]

The problem is that other drivers assume you and your Yaris are slow, so they want to pass. I get passed more often in the Yaris than our other cars.

[nemelek]

Mine is very accurate. Within .5%. Assuming that the speed odometer and the odometer are in sync, the best way to to test them is using the highway mile markers on a road trip. Press the milage reset button as you pass a marker and drive 10 miles. Then compare the difference. Do this 3 times to get an average. You can also drive exactly 60 mph and time how long it takes to drive 10 miles. Do the math and know exactly how accurate your speed odometer is.

[RETRO]

mine is 1.5 mph faster than the GPS

[Stove]

This is the way speedometers are designed. They typically read 3% or more faster than the true speed.

And there is an allowable tolerance of error during manufacture. Federal law is +/- 10% for Speedometers I believe. Most car makers keep it a lot closer to nominal. Some will read spot on and other will read a little high. It's really rare to find a stock car that has a speedo that reads slow. The requirements were set up around the old cable driven speedometers and have never been updated to line up with today's more accurate systems.

On a side note, there was some speculation a few years ago that car makers were manufacturing the speedometers and the related hardware so that it always read faster than what the car was going. This runs the warranty out quicker and before the car hits high enough actual miles to end the warranty. For example, if your speedo reads 5% higher than actual speed then your Odometer is also reading the miles 5% faster. On a car with a 36,000 mile warranty, at 5%, the car has only actually traveled 34,200 miles when the Odometer reads 36,000 (OP's post indicates around a 4.5% variance so he has approximately a 34,400 mile warranty). Obviously, the higher the mileage limit on a warranty, and the bigger the variation form true speed, the more beneficial it is to the manufacturer to have the speedo read higher than actual speeds and register miles faster than it should.

[STC]

Mine is a 2010 with 15" steel wheels...
GPS is dead on!

I'll have to try the mile marker to mile marker for ten miles @ 60MPH to see how it matches up! Thanks

[Buddy Fan]

I find my speedometer to be accurate within 1 mph. As a side note, my old Entourage was off by 3 mph at 65 and my wife's Sonata is off by 2 at 65. I had the misfortune of renting a Dodge Caliber and it was spot on accurate for what it's worth!

[bkrownd]

For example, if your speedo reads 5% higher than actual speed then your Odometer is also reading the miles 5% faster.

That isn't necessarily true. The speedometer needle could easily have an offset that makes it different from both the odometer and reality. (It's possible the offset is smaller and/or more linear than in the old days, though.)

[Bella]

I have an 09' Yaris LB with an automatic transmission. I drive a lot and when going 55 mph (according to the speedometer) I get passed a lot. When I drive my Durango 55 mph, I pass a lot.

So I tracked it with my GPS and when the speedometer says 55 mph, the GPS says about 52/53. I wonder which is correct? My guess is that the GPS is correct or else I've suddenly begun driving like I was 90 years old!

:headbang:

Nah it's a pretty common issue - Toyota confirmed to me that the YR is out by about 6% .. But mine is out between 6.5-8% depending on the GPS I use.

It seems to be a problem with most yaris (and I heard the Fit did that too). One might think it's a safety feature to get people driving slower, who knows...

Odd safety feature, considering if you sit on the speed limit per the speedo you're more inclined to be tailgated, which increases instances of road rage! :wink: I think there is something in the new design rules for Australia re: speedo errors. Though so many people use GPS these days it's easy to pick up where there is a discrepancy.

[IllusionX]

i had lightly smaller tires... 195/55R15. i'd say my GPS is dead on with the speedo.

now that i have 195/60R15's (tires for cheap), i'm a tiny bit faster than i should be. but who cares really?

[YarisPete]

Nah it's a pretty common issue - Toyota confirmed to me that the YR is out by about 6% .. But mine is out between 6.5-8% depending on the GPS I use.



Odd safety feature, considering if you sit on the speed limit per the speedo you're more inclined to be tailgated, which increases instances of road rage! :wink: I think there is something in the new design rules for Australia re: speedo errors. Though so many people use GPS these days it's easy to pick up where there is a discrepancy.

You got the tailgating thing and the Road Rage right! I've been driving faster now that I see the difference.

[Echostatic]

I had the misfortune of renting a Dodge Caliber and it was spot on accurate for what it's worth!

Yep - the Caliber reports its 0mph very accurately! I had the misfortune of passenger-ing in my brother's rented one. 0-65 in about a month or so; the National Car of Florida!

[metalshark]

2007, 15" steelies /w stock meats. Dead on in flat terrain with cruise control engaged.

[Wowzers78]

Both Wheel and tire size can definately affect the speedometer.

I've got 18" Wheels with 215 35 18 tires on them...thought at first that the car seemed like it was going faster cause it was lowered and the ride was more severe...flipped on the GPS and was going 6 MPH faster than I thought I was(speedometer is normally over the speed limit anyways) :eek:

I've adjusted that since, lol

[TLyttle]

I used to repair speedos. The game is to find a calibrated mile (some jurisdictions have one outside of town), and run over it to find out how far out the odo is. If it is accurate, then drag out the ol' stopwatch, run 5 miles at EXACTLY 60mph, then do the math.

If the numbers are out, go to the dealer, and in moments, they can re-calibrate the speedo through the computer.

[bkrownd]

I checked my speedometer against my GPS and a police radar and amazingly it's within 1MPH. I guess the speedometer offset is a thing of the past. They must be made differently these days.

[jpmck03]

Went on a long road trip this weekend.

I set the cruise control for, from my viewing angle of the speedo, 66mph. Checked the GPS and it read 65mph. Asked my wife what the speedo read, and she said it was about 64mph. I'm guessing that looking straight on the speedo would be dead on.

I'd say that with stock 15" steelies, that speedo is awfully close to accurate.

[severous01]

it will always be low for insurance purposes. my camaro was about 7% low, and my jeep was way low until i put bigger tires on it....and then it was perfect. until i put even bigger tires on it then it was over. factory tires for a jeep were 26", i put 29's on it until i lifted it...and put 31's on it. it was about 7% over when i put 31's on it. so...it was about 14% low when i put on factory tires.

[NinjaPirate]

yep mine's out by 4km's usually. Higher speed gets worse of course.
My Scanguage says 60kmh, speedo (digital display) says 64.
It's all stock, and owned from new.
If I do "60" everyone passes me.

[Yaris Hilton]

Yes, the speedometer's made for straight on viewing. I set mine about 1 MPH high from my seat position when the needle's straight up and it's right on when looked at straight.

[Yarisduder]

In my car the speedometer is set at an angle so that it's pretty much straight on from the drivers seat, I'm sure all of yours are the same. Against the GPS it reads about 6% fast, which is almost the thickness of the needle, so put the slow edge of the needle on the increment marker and it's good.

[Yaris Hilton]

In our 2007 S model sedan and two 2009 base model sedans, the speedo is set exactly straight facing the center of the back window. No tilt whatsoever. In the 2002 Echo it was angled toward the driver.

[Bluevitz-rs]

The speedo NEEDLE will have a +- variance of approx. 5%. It's the ODD you should be measuring. And chances are it too will be off.

A few years ago I drove in a convoy across Canada from Edmonton AB to Toronto ON. I was driving a brand new '06 Tacoma, and my co-worker was driving a brand new '06 Tundra. At every gas station I had about 10-15 more kms on my trip meter than the Tundra did. That was only over a 250km range.

There's nothing anyone can do to correct it other than you changing your tire sizes to accommodate the difference.

[Yaris Hilton]

In my car the speedometer is set at an angle so that it's pretty much straight on from the drivers seat, I'm sure all of yours are the same.

You're absolutely right. The cowling around the speedometer cluster is straight, but the cluster in the back is slightly angled toward the driver. Not quite straight on, but it's tilted that way a little. I'd never noticed, thanks! There's still a little parallax, and I find mine's about right when the low side of the needle is on the speed increment marker as you said.

[yaris2010RS]

okay, so i only went through the first few posts so if it was said already im sorry.


GPS are a good guidline but are no where near accurate. yes they are close but for a test like this not close enough. take for example my GPS, i own a tomtom710. i have had times it is saying higher then my spedo and other times saying lower. GPS are only accurate to a distance allowance. some may be two inches, others may be 2 meters, that will make a huge difference.

a public fact is almost every car says ur going atleast 2km/h faster then u really are, the exact reason im not too sure of but there are most likely many.

really it comes down to so many factors are involved its close enough.

and those stupid digital side of the road speed indicators are the worst!

[birdman]

People pass my Yaris then slow down. It's a ego thing I guess.

[birdman]

Speedometer errors of 5 mph where once required by law to fool the driver into driving slower. Safety regulations of the time. I don't know if this is still in effect today though.

[sleey0]

Old thread, yes BUT mine does the same with my ecometer. Says it's about 4mph off.

I don't really care though.

[tashyc]

I also notice this problem, I was wondering if the placement of the speedometer has anything to do with the inaccurate reading. Since the speedometer is on an angle in comparison to the normal line of sight you dont percieve the speed the same way you would if you were looking at the speedometer without the angle. this results in you (the driver) thinking that you are going faster than you actually are, or the passenger thinking that you are going slower.

[dj92]

The Speedometer on mine is quite inaccurate, too, but I think this is for psychological reasons:
I have built a gauge that shows me some OBD data and the speed I get to see there is the same as what I can measure using GPS.