How about flying your car on the ground?  This exciting activity has really taken off with Tech Ed Teachers.  It's a rocket with wheels that is propelled by a "B" or "C" rocket engine.  You can have students build them in teams and then attempt land speed records of their own.  All the basics are included and you will love watching them go!

(Note: Rocket car must be launched outside!  Please allow 300-500 feet for run depending on the size of rocket engine).