Rearview radar

  Everyone knows about radar detectors but what about those pesky cops who pace you from behind. I don't know how many times I have been driving, maybe speeding, and I look in my rear view, and theres an officer right behind me! There should be some kind of detector for cop cars and bikes behind your vehicle. Maybe an optical sensor, or something that can detect what kind of vehicle is behind you, since all vehicles have different headlight placement, etc.