Speedometer/Odometer

[Jugarum]

My 08 Camry speedometer reads 40 MPH when all the radar speed signs I pass show about 37 MPH. would this discrepancy also apply to my odometer, or is there no direct relation between the two?

I have OEM size wheels and tires, 10,000 miles of use.

I'd hate to find my MPG is almost 10 percent off on the high side.

TIA

[bandit]

Ummmmm...you use those speed signs to gauge your actual speed?

I dont even go by the speed signs. If you ever pull over to the side of it with no cars around, it will calculate the speed of cars coming from the other direction or cars passing by it. Theres times where it clocked me going 60 when I was only doing 30. If you have a radar detector, these speed signs will also set off the detector.

[njerald]

Regardless of the previous answer, my speedometer reads 2-3 mph higher than the radar boards and 2-3 mph higher than my GPS.

I've never checked the odometer to see if it carries over to mileage.

[skyxliner]

simply put, your fine.

[red_lavalamp]

I was wondering about this myself. The scangauge says I'm going 2-3 mph slower too, but that's getting it from the onboard computer so I don't know what's up. Seems like there is a lot of evidence that says the speedo is off. I don't know about the od. I guess we'd have to check that with a GPS.

[workerant]

Can't trust GPS cause it's not accurate. The only thing that matter is the Police's speed radar. So call 911 and ask for a police to come check your speed.. make sure you go speed limit and ask him how much it's off by.

Most judges here will let U go if U R not 10mph over speed limit.

[Jugarum]

What's the best way to check the accuracy of the odometer?

I know I could find a measured mile on a freeway somewhere (accuracy also unknown), but I haven't found one and I don't have time to make one myself on I80.

[squeakers]

there is a product called a yellowbox. its used to correct spedos. and not those spedos

http://www.blackrobotics.com/

[Jugarum]

Thanks for that. That's an interesting product.

Does anyone know if the Toyota Camry speedometer and odometer operate together with the same margin of error?

[djnk954]

GPS are very accurate, but they give you your "movement" speed and not your "wheel" speed, which is your speedometer speed. For example, if you are going up on a high ramp your GPS will show your movement, which will be slower then your actual wheel speed.

[tvsjr]

In general, what you are seeing is simply the gauge/escutcheon/etc., not what the car computer is actually seeing. The fact that a Scangauge reports 2-3mph slower backs this.

I checked mine with a Stalker ATR KA-band handheld radar gun - typical police issue. The speedo reads about 3mph high at 60mph (60mph indicated, 57mph actual). However, that discrepancy is lower at both 30 and 80mph.

You can be assured those signs (which set off radar detectors because they employ typical police radar units - most are built by Kustom Signal) are far more accurate than your speedo, assuming you are the object being measured and no other "odd" phenomena occur (you have to know what to look for when using a radar - that's why the cops go through classes.)

GPS is better than speedo assuming a decent GPS engine, good sky view/several satellites locked, and a steady speed. GPS will lag behind changes in speed by a few hundred milliseconds.

[workerant]

When doing about 0 to 60mph, my gps is less by about 3mph to my speedo. It's most accurate when I do about 90 to 120mph. From than on until 500mph is an unknown but above 500mph to about 700mph I have checked and it's accurate too.

Many times I wish I could see how much I can push before the engine change gear. The best mpg is when the car don't have to down gear. But when going up hill I want to keep the speed as much as possible without having the car down gear.