I have seen people say that certain lighting systems on cars are illegal, at least in some states. Like the skirt lighting that lights under the car. I suppose it depends on how a bicycle is classified in a given state and if the vehicle code has been changed to get rid of these kinds of decorative lights. I haven't been doing as much highway driving as I was doing a couple of years ago, but in my recent trips I haven't seen any trucks decked out like a Christmas tree like I was seeing before.