I want to put a 12x12 drain where a car could potentially run over it. Will this support a car? If not, what would you recommend?

If the catch basin is going to be installed in a location where cars are going to drive over it, you will need to install the basin with a minimum 4" wide and 4" thick concrete collar around the top of the basin. The standard plastic grate will support the weight of a sedan or small pickup/suv if the car happens to roll over it. If the car will be parking or frequently passing over the grate then you will want to use either the ductile iron grate (NDS part #1213) or the galvanized steel grate (NDS #1215). These will do much better in a location where they will see frequent traffic. Please note that that the ductile iron grate will rust over time.