I have a question for anyone who has actually used one of these GPS units for this application, measuring vehicle speed of travel: How fast does it update? How fast does it respond to changes in speed? Is it only good for average speed on the highway? If I am traveling at 30 and then speed up to 40 how fast will it register that? I assume that there is some lag and averaging going on and it would not really work very well in terms of getting an accurate speed reading all the time. But I don't know.

Thanks,

Mike

__________________
1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra