I'm not really up to date on motoring gadgets , so can some one please explain why I keep seeing more and more cars with some sort of round tube running across the vehicles  back window, and what are the small round holes drilled into the car rear bumper for ? , and do I need to have them on my car . 

 

The holes at the bottom are for firing smoke canisters and mini torpedos from.

 

The thin strip produces an invisible force field to prevent damage to the car if somebody decides to jump out of a high rise building above the car

A friend refused to accept his car back from the workshop until the sensors in these had been repaired after he had been rear ended. I cannot remember exactly what they were for but it's presumably safety related.

Probably a stack of 'passive' road rage stuff:

The window super bight led light bars specifically placed in the line of sight to blind the drivers behind.

The bumper holes good for placing quad pairs of more blinding lights.

Google "rear bumper diffuser holes".  Also called speed holes.  Makes a little riceburner car go faster.

 

 

About as useful as this. Very popular in the eighties in Germany.