What is the shortest distance that a radar detector can detect radar and still be considered a good detector. For example the Rx 65 can detect most bands over four miles. I know the longer the distance the better but what is a good distance if you have a detector that is not that sensitive. I mean a good distance for a average person going a little over the speed limit not going 120 mph or so which would not help. Just trying to get my wife a detector thats the reason for the question. Any light you could shine on the subject would be greatly appreciated.