I use the "Speedbox" app... Was very accurate in my real car, however you need to span a fairly large piece of real estate for it to show an accurate measure with R/C's.
Nice, there enough time with no cars though? And what gravel pits?
at the end of springfield, towards the floodway, by the CP Mainline. the East end of springfield, and I went on sunday, there was like NO traffic, it was awesome.