Grant's+Why+Nots?

What is the best way to reduce speeding on the highways? make cars "know" the speed limit and not go faster than that. the cars would have sensors that detect the limit via satellite. Countless car batteries have succumbed to the carelessness of car owners who leave their headlights on. What's the best way to tackle this problem? the cars will have a timer that after ten minites they would shut off
 * **Reduce speeding** [P0019]
 * **Car Headlights** [P0005]