Spinner,
I just used a couple of small pieces of double sided scotch tape to put it on. It's not on well enough to drive, I'm sure it would fall off. I didn't have the nerve to remove the non-stick plastic off the back and really stick it on the car. Taking it off would be a major pain. Also, there may be an environmentalist out there (especially in Kahlifornia) that might take offense and do who knows what to the car.
DrDJ
In Goergia you could now drive in the HOV lanes.