don't buy the cheap one.. they worth nothing !! And please.. don't speed in viginia... got cought doing 160 km/h in a zone of 110, and we went to court for that ! at 2:00 am a ****ing sunday !! Our little speeding costed us 1500 $ US... Just don't speed in virginia... (oh, and RD is not legal in Viginia, we learn that the hard way too...)
But all the other states, you'll be fine ! (did Ottawa Miami, with RD, average speed of 170 km/h.. )
Your best shot is to get between the big trucks. After 10:00 pm, it's pretty scary out there ! All you see on the 95 after 10 pm is truck truck truck and truck again ! And they speed up to 180 !!