I posted a project yesterday showing how the Hot Wheels Radar Gun works and implementing a serial interface for it. Since that time a double epiphany has struck me, one for an easier way to interface it and the other for a slight bug in reading the radar.
If perchance you have downloaded the code and actually plan to use it, you may want to get the latest version when it's posted (the next day or two). Depending on how the spirit moves me, I may include more detailed instructions on the easier interface, but don't hold your breath. All the other information is correct as far as I know, and the bug only affects using the radar in pulsed mode, not in steady mode.
Sorry about that. They say the ancient temple builders used to consciously incorporate mistakes so as to not offend god. Probably what I was doing, too.