I think this is a wonderful idea. Brilliant actually.
I always park and get out of the car when I go to a fast food restaurant and quietly cuss those who sit in their cars, in line, running their engines for 10 or 15 minutes at a time.
The price for their convenience is poorer air quality and higher fuel prices. I think fast food restaurants should just shut down the drive-through. It should not require a law to force them to do so.
Of course, I think all lights at all intersections should be 'smart' lights. Where they are not run so much by timer, but by actual traffic. It is very irritating to sit at an intersection with zero cross traffic for up to 3 minutes due to a light being on some timer.
I also think cities should be placing light status indicators in areas where the lights cannot be seen from a distance, so those of us who like to coast as far as we can to a red light can do so.