Quite a while back I had a state trooper clock me using a radar gun since he claimed it was more accurate than his speedo. I ran acoss one of the portable radar indicators setup in the median of the road. Never one to waste the opportunity, I tried getting my speed from it too. I made 10 passes making sure I was the only vehicle it should be picking up. The state troopers radar gun and the portable radar sign both indicated my Burgman 400 speedo is off by about 6% rather than the expected 10.