What would be the dimensions of your ideal wheel stop/curb stop at the end of a parking spot?

These are the concrete rectangles at the end of parking spots to make sure you don't park too far into the parking spot. I think they are often too tall and can damage the front end of cars with low ground clearance. Personally I think having them 2" tall would make them prominent enough to stop without running them over when entering the parking spot at a reasonable speed without hitting the front end of cars that are low to the ground.