Funny how, just the other day, I was pondering if anyone still used radar detectors.
As for GPS systems, I have a concern. One of the menu selections (at least on mine) tattle tales the highest speed driven. The thing could darn near be used to incriminate you on speeding, if it actually memorizes where you drove at while doing what speed. Be even worse if it communicated this information in real time to the local authorities.
I do say 'darn near', because a friend once mentioned a flaw in this system. If it mis-located on start up and then corrects itself, it can become confused with the physical reality of MPH. He said the unit recorded a speed of something like 23,000 MPH! Nice to know that when the first Warp ready ship is put into use, GPS will have been long since ready to chart it's speed.
Actually, I would rather have a Speed minder device over a trap detector. Shouldn't be too complicated. An electric eye that looks for those unique white, rectangular Speed Limit signs and identifies those gigantic numbers via OCR software. It compares this number to the speedometer and does something like blink a light when the meter is above the sign's posted limit. Go way over and a buzzer is included. Here in California, the tollerance is now a tiny 3 MPH over the posted limit...and that is when Zero Tollerance is not in effect. I know it used to be 5. And, it might have even been 10 at some point. But, right along with the tightening restrictions on phone usage and smoking, it's a meek three MPH. At least, there's Cruise Control.