My wife and I took a drive in the country yesterday, and had a pleasant evening in Lawrence Kansas. Took in a garage sale and I passed on some Onkyo/Mitsubishi/JBL/Emerson(tube) gear. If you are ever near that town, check it out, esp. Keif's (an audio salon).
Anyway, we were cruising down K-10, and I was checking my speed with the GPS, the Honda's own speedometer being nowhere near accurate. I thought back to a much older Honda Accord, so old there were still waiting lists, and one of my friends told me, "I hate you!" when she found out I had a new one. I took a trip out west in it and checked my speed with a stopwatch and a railroad time/speed chart - milepost to milepost. Old technology, but I think the older Honda had a better calibrated speedometer.