Speedo reading low?!?

[Michael McLaughlin]

I got pulled over last night. I was doing a quick round trip between 
home and a town about 75 miles away, on two-lane rural highway with a 
60 mph limit (for you Northwesterners it was between Pullman, Wash., 
and Spokane). I'm Mr. Five Over, and had the cruise control set right 
at 65. On the way up I came across a Washington State Patrol cruiser 
heading the other way who didn't seem to be concerned with my speed. On 
the way back, I was also doing 65 and came across a WSP cruiser heading 
the other way again. This time, he turned around and pulled me over. 
Turns out it was the same trooper -- he said he didn't have a chance to 
turn around the other time, and recognized my car coming back (I guess 
Pelican Blue really is distinctive).

Anyway, he told me he clocked me going 70 (both times). I was really 
surprised, of course, and told him I had the cruise control locked in 
at five over. He took my driver's license, was back at his car for 
about a minute, and let me off with a warning and a recommendation to 
slow down a bit.

Finally, I get to my point.  :-)  Is there any chance in heck that my 
speedometer is reading low? It I recall correctly, German speedometers 
tend to read high, and I have stock-size tires. I have a feeling he was 
using a bit of hyperbole to get me to slow down, since if I really was 
going 70 he probably would have ticketed me.

So, what do you think? This is making me a bit paranoid. Next time I 
come across a speedometer check area on the freeway I'm going to time 
it.

Thanks,
Mike

P.S. He didn't seem too concerned with my lack of front plate, nor my 
illegal window tinting.  :-)