Before reading the thread I thought you were asking about Dodge Neons. A good way to start would be checking with the DMV/BMV for your state. For example, I was able to find out via Google that Ohio allows neon lights but they must not rotate, oscillate, or flash, and state law does not prohibit the use of colored neon lights under your car as long as they do not interfere or blind other drivers. So why not Google search: neon lights motor vehicles yourstatehere. Best of luck!