The folks at Mercedes-Benz like to think of their F-CELL hydrogen fuel cell car as being invisible to the environment, so to promote it, they have built one that can practically disappear.
First they covered one side of the car with LEDs, essentially turning it into a giant car shaped TV screen. Then they mounted a camera on the other side, and displayed whatever was beyond the car onto the LED screen. This has the effect of making the car almost invisible, especially when the angle and lighting are just right.
I wonder if this could be adapted to make my own car invisible to the Highway Patrol?