That Garmin radar think is so lame it's not even funny. First off if a car is going 60 mph coming up behind you and it has a 140 meter range, how fast is that vehicle going to cover that distance? 5 seconds! Not a lot of time to react, plus it doesn't tell you if the vehicle is on a collision course with you. The other issue I have with it is that it only hits 65 lumens in the daytime and at night it goes down to a measly 29 lumens?
I know from experience that a 65 lumen light in the daytime will get washed out in direct sunlight, I also know that 29 lumens at night is...well you might as well just use a reflector! My tail light puts out 300 lumens, that's really the least amount of light you should have in broad daylight, at night I leave it at 300.
So why pay $130 when a $15 mirror will work just as good if not better, and a $50 300 lumen light will protect you far better with it's huge visibility factor.
That's just my opinion.