I remember there was a small town (sw co?) we used to drive through years ago for work that had a plywood cutout of a police car on the side of the road outside of town. I have no idea if the police put it there or some resident did.

I thought it was brilliant idea. I also thought, why not put dummy cars here and there on the highways and move them to different spots each day. Just junkers painted up. People would see them and slow down. You would need some real enforcement as well so folks wouldn't just blow them off. Mission accomplished, except for the brining in revenue part.