Thought Id comment since my career field has kinda made me a little knowledgeable in this area....
Radar detectors are a waste of money. Read my whole rant before you move one. As Ill address pros and cons of using them.
First of all There are four types of speed detection currently being used.
Radar, Lidar, vascar and pacing.
#1) Radar
Radar can be used to catch your speed from a police vehicle whether the police vehicle is moving or not.
Cons:
The problem with using a radar detector to avoid being caught by radar is that when a cop is using radar, his radar is in two modes. First it is "on" and second it is on "hold" (not sending out any radar signals). When he sees a car that appears to be speeding, he releases the "hold" (sending out a radar signal), your detector goes ape shit because the two of you are within 100 yards (usually). You can jam the brakes but unfortunately its to late, he already got your speed before you pressed the pedal.
Pros:
If the cop is using his radar but not in the "hold" mode then your radar will detect him from a far enough distance that he cannot achieve your speed.
Most cops now use "hold" when they are actually looking for a speeder so your radar detector will be useless. Unless the cop is a rookie and he releases hold at every car that goes by. In that case your radar detector would go crazy then off then crazy then off, long before he can catch your speed.
#2) Lidar
This is basically a laser gun that sends two range finder beams at your car and measures the distance between the two ranges. It then calculates mph from the distances and the hundredth of a second between the two.
Cons:
The Lidar unit only sends a signal when the officer is aiming it you. When your the lone ranger, mainly because you've blown everyone elses doors off, hes got you because the radar detector had nothing to detect until it was aimed at you and at that point its to late.
Pros:
The detector will help when there are lots of cars out on the road and the police officer is constantly aiming it at cars. They usually do this at the bottom of a hill when you cress the top of the hill hes got you.
#3) Vascar
This is outdated and you could beat any vascar ticket in court. It also usually involves an aircraft relaying our speed to an officer.....
#4) Pacing
There is no pro to having a radar detector here. Your basically screwed. Many police agencies are using covert vehicles, Tahoes, silverados, camaros, mustangs, etc. they drive on the highway and when you pass them they simply pace you which a radar detector can obviously not percieve....
My opinion for what its worth is this, If you are an average driver who blends with traffic and speeds to pass a car here and there. A good radar detector will save you from that once or twice a year when you speed up to pass someone. If your a wreckless driver that does 90 everywhere he goes and are always the first one to take off from the light then your wasting your money. Being the fastest car on the road and always the lead car makes your radar detector usless because your the bait for everyone else. When you fly by the cop he either activates the lidar or takes the radar off "hold" sets off your detector and everyone elses behind you. Unfortunately hes already got your speed........
