Speedo Not Calibrated Or Incorrect?

[Leolus]

I have reason to believe that the speedometer on my 07 IS250AWD is not calibrated or showing the incorrect speed. I say this only because I've set the speed and passed several visible radars and the speed has been off by 1 to 3 notches, signifying a difference anywhere from 2 to 6 mph. The car only has 2.3K miles on it and I was wondering if there is a chance that this might self correct itself. Also, the car feels really slippery. What I mean by this is that 80mph does not feel like 80. It feels much slower. Is it possible that this could just be in my head and I really am going as fast as the speedo states, or has anyone else had this problem? What should I do and how should I go about getting this problem fixed? I didn't know how to do a search for this and if someone has already posted this topic, could someone please direct me in the right direction.

[bartkat]

First, those radar signs aren't all that accurate. There's a time lag on the readings. You can see them range over a few MPH as you approach. They're also reading the speeds of other cars in traffic so the speed you see may be that of another car.

As for feeling slow at 80 mph, that's part of the stable nature of the car. They feel pretty solid at 100 and above as well.

If you want to test the speedo, go out on the interstate with a stopwatch and measure times between mile markers, maybe even 3 to 5 miles of them while runing on cruise conrtol. Use the distance traveled and your time to calculate your MPH. That should be pretty close.