2007 ES 350 Speedometer Error
 

I have noticed that when I go passed one of those unmanned radar units that my speedometer is not reading what the radar says. This happened once at 25 mph indicated on the car…the radar read 23. Then again on the freeway the speedometer read 70 and the radar indicated 68. I checked with my local dealer and he said this is common to all Lexus models (liability Issues is what I was told.) I do not know when this policy started but I believe it was after 2003 since I had a 2003 ES300 and do not recall this problem.

Q. Has anyone else experienced this?
Q. Is there a fix for this? My Lexus dealer says “no”

It is not a big deal, I suppose, except in order to drive 35 I have to indicate 37 on my speedometer so I can keep other drivers from piling up on my bumper :), which is what made me suspicious to begin with. It is just a bit annoying.

when i run past those radar trailers, it clocks in at 25!

Is there a digital speedometer that I don't know about? The graduations on my speedometer are so fine, I am not sure I could tell the difference between 23 and 25.

It would be a nice feature for the NAV

I've noticed the differnce also. The radar trailer on the Air Froce Base I'm at consistently shows 33 mph when I'm at 35 mph on the speedo.

Unfortunately, speedo calibration is not an exact science. It is generally done by defining a set tire circumference (or diamater, or revs per mile...essentially the same thing) into the engine's ECU (or PCM...pick your acronym).

The part that isn't exact? Your tires. They're taller or shorter based on either sidewall compression or amount of tread. The former...inflation pressure and payload both play a role. The latter...simply how many miles you have on the tires. Even brand new tires of the same size from different manufacturers will generally differ in circumference.

All of that is on the vehicle end. There's no guarantee the radar detector is calibrated correctly. Bottom line...as long as you're within a few mph I wouldn't sweat it, or certainly wonder if there's something wrong with your car.

A portable handheld GPS system (like a Garmin Trex) will be able to accurately measure the speed of you car. Too bad the ES 350 nav doesn't have real time speed readings.

Everything is fine.. Reading little more than the actual speed is expected.. It's a new law.. It started in Germany and now all manufactures are doing it.. Don't worry :)

Thanks for all of the quick replies folks.

at least there is a two mile difference than what the cop that has pulled you over thinks you were driving. complicated sentence gramatically. lol i had to rewrite this 2 times. :D

AHH, I have a 1995 ES and its also off by i believe 2 MPH, that just could be cause my Lexus is so old though??

I have also notice that if I drive 60 MPH (or whatever) consistently for a while after resetting my Average Mile Per Hour (on the digital display panel), it will always read about 2 mph differnt than what the analog speedometer reads. I would at least like them to be the same, if it won't match the radar.

I don’t know?? I checked the Speedo in the GS with a portable Garmin V GPS and the MPH matched. The Speedo shows 40 and the GPS shows 40. A good thing to know here in SoCal since I heard the new laws went into effect on July 1st - no more than 3 MPH over the speed limit here.:nono: That’s got to be wrong!!!

FWIW – maybe this can be of interest to others riding on 20’s. After posting my above post I noticed that my 20’s are just a little larger in circumference than the stock tires. Well there you are my tires are turning at a slower rate of speed than others running on the stock tires. That would explain why my car shows the correct speed in the Speedo. Probable if I had the stock tires on my car the Speedo would show 2 MPH over actual speed too.

All car companies do this. It's partly to save your ass from a possible speeding ticket. The higher the speed, the higher the difference. BMWs are really bad about this. A friend was driving his M3 past one of those speed guns on a highway going 90 as indicated by the speedometer but the speed sign showed 83.

my gs is reads high 2-3 mph too. I wonder if over time it makes the miles add up higher than they really are...?