Once in a while I get a big number after I turn on my 2610. It'll think it's acquired a position, but it's wrong, and when it corrects, it thinks it moved really fast to get there. 650+ is my best so far.
My name on the Bikeland web site is 1393kph - for the obvious reason.
Once had a smartass cop who though he would be cute reach over and press the appropriate buttons on the 276c - the look on his face when he saw that number was priceless.