How accurate is in-patrol-car radar in opposite direction?

I am wondering from a scientific perspective how accurate a speed reading can be when made from a patrol car by an office driving solo, not at a consistent speed, measuring the speed of an on-coming vehicle which is accelarating having made a 90 degree right turn. It would seem to me that with the speed of both vehicles varying, the measurement would be likely to be inaccurate, but I am unfamiliar with the technology.

Hi

The radar guns we sell require the user to be stationary. In theory, yes, you could devise a computerized system to take into account all the variables, but this would be cost prohibitive for most police departments.