How accurate is your speedometer? If you are off, how much and in which direction? Assuming the "YOUR SPEED IS" signs on the highway are accurate, my speedometer shows about 2PMH faster then I am really going.

Can the speedometer be calibrated and changed?

 

I have only checked mine by comparing it to the readout on a Garmin GPS. It is my understanding that these are pretty accurate. It shows that mine is about 1MPH off. If the Lexus says 71 the Garmin says 70. So mine says I am going about 1 MPH faster than I am really going. I have tried the stopwatch at 60 from mile marker to mile marker and it is difficult to be very accurate.

By the way, my ES300 was identical.

 

Yes, your speedometer can be calibrated. In fact, if you change tire size to a different diameter tire, you should have it recalibrated to match the tire size. (Actually, I haven't checked our specific speedometer, but it is common to do so. Truckers have to do it whenever they change to different sized tires.)

 

+1 iolmaster, all three of my Lexus's are 1 mph off. The Garmin will always be more accurate than a stopwatch

 

Sure. It can even be certified. How much money you got?