The device would mimic a standard license plate when the vehicle is in motion but would switch to digital ads or other messages when it is stopped for more than four seconds, whether in traffic or at a red light. The license plate number would remain visible at all times in some section of the screen.
Not only is this a bad idea, because it exploits the public in yet another way, but who chooses what ads are displayed on a particular license plate? You want to put ads for the Sierra Club, Humane Society of the US, and PETA on my truck? Fat chance. I might not scream quite as loud if the ads were for Remington, Shakespeare, or the Big Sky Brewery in Missoula, but I'd still be more than a bit pissed.
Double-plus ungood idea.