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Discussion Starter · #1 ·

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eeto........?
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you do know that GPS have errors right? A DGPS would decrease this error, and there are lots of factors that would cause these errors. Such as multi-path error, ionosphere and clock error to name a few. Plus your current position on earth is a factor in relationship to the 4 satellite which your GPS receiver must connect to.
 

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Discussion Starter · #3 ·
I actually know a fair amount about satellite navigation and data collection. I've been using various forms of satellite navigation since 1982. Some of my data was collected in DGPS mode. Two different GPS's were used. The error was constant. Always a reading of 66 mph on the GPS and 70 mph in the car. Data was observed over a 5 day period on a 3000 mile trip.
 

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2005 Camry XLE V6
Lexus ES350
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I think it may not be an error to have your actual speed be lower than what the car's speedo indicates. I've notice the same thing with my Camry (all three of them) - their speeds seem to be between 3 and 4 mph lower than what is indicated on the speedo.

My '93 has about a 3mph lower actual speed than indicated by the speedo (Police radar gun confirmed this) -- no I didn't get a ticket, it was a test setup a while back.

My '98 had about a 4 mph lower. Same with the '05.

This may actually be a good thing, considering that some people actually think going 65 is "slow" and 70 is just right. The fact that the speedo can fool you into thinking you're going faster than you really are may be a safety "feature." I remember my first car, an '89 Sentra had a 5mph difference between actual and speedo :eek:

Maybe I'm wrong; perhaps all my cars are defective. It's just what I've noticed so far seems to be what LandShark is seeing as well. So if someone else know more about this than I, please educate me.
 

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TN の がしょう
2015 Camry XSE V6
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Same here. My friend is a cop for the LAPD and he offered to clock me because I noticed that the radars on the streets clock my car 4-5 mph slower. It's true, all Gen 5 camrys reads it 4-5 mph faster.

My best guess would be this. Toyota probably did it to give the car a better mileage by showing the drivers that they're actually driving 4 mph slower than the speed shown on the odometer.
 

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TN Pussy Man
Camry
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^ no, it's purely just because after a certain speed, the speed sensors aren't accurate


do a search and you can see that this topic has been discussed before as well....it's just the way that cars are designed- it's the same with all cars, and the speed sensors can also become uncalibrated as well

hence, that is why police cars in states/provinces where they can clock your speed by pacing, have to have their speedos calibrated at specific time intervals
 

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All cars from all companies have this problem. There was an article in either "Car and Driver" or "Motor Trend" about this topic. I think the range was between 2-6 mph. The average was 3-4 mph.

It's really not big of a deal. If you really want to be accurate, you'll probably need to play around with wheel/tire sizes.
 
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