Better Check your Odometer!

[xdforme22]

Picked up the paper and saw this article, what a mess. Apparently this is not necessarily limited to Honduh either.
LINK:http://www.usatoday.com/money/autos/2007-02-19-odometer-usat_x.htm

[Seinster]

Question:
If the speedometer reads a faster speed than what the car is really doing (eg. 70mph on the speedo = 65mph in real life), would the odometer correspond to the speedo. or real life?

[ghrpdx]

I know my speedometer always seems to be roughly 3 mph off. That is indicated by the radar speed signs we have around town that show our vehicle speed. Not only is the indicated speed incorrect, but our cars also log all of our mileage in reverse. If the incorrect speedometer reading affects the final outcome of the odometer, that means we are also getting roughly 5-10% worse fuel mileage than our estimates.

[Doohickie]

It depends on why the speedo is reading high. If it is a problem in the speedo itself, then the odometer is not affected. If it is a problem in the signal that feeds the speedo, it probably also affects the odo.

On my Escort, for instance, it has the old-fashioned speedo cable. It would spin at the proper speed, but at colder temps the speedo would jump up to crazy values (due to a mechanical interference in the speedo itself) where the speed would jump from 60 mph to 90 mph or something like that. The odometer didn't move any faster though, and the cruise control keep the car at a steady pace; only the speedo was affected.

I'm not sure exactly what mechanism drives the Elantra speedo, but there is a chance that it may read high or low compared to signal feeding it, but the odo would still be accurate. The odo is more of an absolute number: so many ticks = so many miles. The speedo involves dynamics and time, so it it more prone to inaccuracy.

[xdforme22]

The speedo is not reading high, the odometer is.

[ghrpdx]

^^My speedometer reads high ... and I have the proper sized tires, too. Like I said in my post above, the reading has been verified via our radar speed signs ... then again, the radar signs might be incorrect and my speedo is accurate.

[mtlelantra]

My speedometer reads high as verified by GPS. Actually haven't compared the odometer. Next time on a trip...

[silversharkXD2]

in all technicaltiy, wouldn't it vary based on the thickness of your tread. The mileage that is. I don't know if it is enough to matter, but if it is based on the number of revolutions, that value would change as the tire decreased in diameter. Am I correct in this thinking? Like I said, it may not matter enough, but would that be the case reguardless?

[WytchDctr]

Ive checked my speedo against a GPS and those sign things. Dead on even at slightly higher than normal speed, ha.

[NovaResource]

Generally, the speedo and odometer are run from the same gear and/or sensor. If one if off, so is the other. Now, if the speedo is fast (ie: indicated=70mph, actual=68mph) the odometer will be high (ie: indicated mileage = 70 miles, actual mileage = 68 miles).

For the most part all speedos and odometers are off slightly. Things like tire wear and tire pressure affect the tire diameter and circumference. Also, not all tires are identical. Take 2 identical sized tires from 2 differnt manufacturers and you will get 2 slightly different diameters and circumferences. Add in aftermarket wheels or non-stock tire sizes and the speedo could be way off.

I think any speedo/odometer with an error under 3% is good. Over the life of the warranty (100,000 miles) that's only a possible loss of 3,000 miles.

[BobMs_wht2k2]

I've been running oversized tires forever. My speedo is currently about 5-7% (depending on sign) slower than actual. I like it like this personally. I run all highway at highway speeds (65+) so this makes me run with traffic at slower engine speeds and less miles on the car. So I guess technically I should be closer to 80k than 70k. But the engine/drivetrain has only run 67k.

[xdforme22]

I'm just wondering if anyone read the link in the first post. I thought it was semi-amusing, but maybe its just me. I do not have any problem with my speedometer or odometer.

[BobMs_wht2k2]

Amusing? No. Sad and rediculous that litgation lawyers run this country because people are too lazy to work for anyhting, yes.

[lilo shark]

interesting faq. mines slower be 3 miles on the radars.

[silversharkXD2]

Amusing? No. Sad and rediculous that litgation lawyers run this country because people are too lazy to work for anyhting, yes.
Ya know, my grandfather is a big local political buff. used to run campaignes and stuff. He was the head organizer in western pa for dole/kemp(i dont know if that says much, but hey, he had the job) He was talking to a neigbor a few years back about why he took all the bush and pro republican signs off his lawn and stickers off his car. The guy had two words to say "torte reform"! just goes to show that lawyers will comprimise their very soul, their core values, all over making a buck...LOL.

And I just had to laugh at this link after my coment on pro US car makers...how much you want to bet that this was influenced by someones pockets getting lined. I mean come on "all the detroit brands were dead on"! but the honda...wow they really screw you by stealing your wallet...LOL come on! I had TWO chevy trucks and ONE ford that were off every time based on those radar signs! now, i wonder how acurate they are. They are just there to advise you...but every one was off!

[Doohickie]

Generally, the speedo and odometer are run from the same gear and/or sensor. If one if off, so is the other. Now, if the speedo is fast (ie: indicated=70mph, actual=68mph) the odometer will be high (ie: indicated mileage = 70 miles, actual mileage = 68 miles).

For the most part all speedos and odometers are off slightly. Things like tire wear and tire pressure affect the tire diameter and circumference. Also, not all tires are identical. Take 2 identical sized tires from 2 differnt manufacturers and you will get 2 slightly different diameters and circumferences. Add in aftermarket wheels or non-stock tire sizes and the speedo could be way off.

I think any speedo/odometer with an error under 3% is good. Over the life of the warranty (100,000 miles) that's only a possible loss of 3,000 miles.
Not entirely true.

On the one hand, if the cause of the speedo reading high is a problem with the cable (or wheel speed sensor), then yes, it will make both instruments read inaccurately. But if the problem is with the speedo itself, the cable may be spinning the right amount to give accurate odo but your speed readings are off.

To get an accurate odometer reading, all the odo has to do is count distance in the form of sensor clicks (or cable revolutions). To get an accurate speedo reading, the speedo has to distance AND time. There is only one potential source of error for an odo, but two sources of error for a speedo.

[HYTECH]

I've had a few people complain about the speedo reading wrong. We would have to check it on a dyno at 30, 60, and 90 MPH and they alow 7% with new tires properly inflated. One time a customers sonata had tires worn to the wear bars that was 8 miles slow reading 60 and we put tires and rims off of a new sonata on it to test and then it was only 1 mile slow.

I have had two 2007 elantras with speedometers off by 10-15 mph when driving above 50mph. and I had to change the inst. cluster to a different part number they make 6 different ones (I think it was some mixup with the programming)

[Ugzz]

my stock wheels tires run 2-4mph fast if the "your speed is _" signs are accurate. Which i know all of them are NOT, cause i saw one register me at 40 when i was doin 30 and there was no one else around.. but other then that they always read 2-4mph lower then my speedo sais.. and i am almost Always cruizing when that happens

[04 elantra cvvt]

Amusing? No. Sad and rediculous that litgation lawyers run this country because people are too lazy to work for anyhting, yes.


+1 ^^^

[2001GLS]

Ive checked my speedo against a GPS and those sign things. Dead on even at slightly higher than normal speed, ha.

Same here..... my 06 Sonata speedo always matches up to the GPS speed.