I tried making a land speed car out of blocks of balsa as a kid. Very arrow shaped. The trouble was, that any road surface imperfection made it bounce in the air. Could a similar car as the above work on black powder engines?
I've built dozens of rocket cars over the years, some line-guided like the Blurzz cars, others free running, with varying degrees of success. Some were built with rocket parts, others using model airplane type construction methods, a few from aluminum and a couple of plastic model conversions. Several use motor ejection to deploy a chute, shortest possible delay was the best bet!
I found that a few of the keys to keeping them on the deck were to use some type of suspension system to absorb the bumps, a bit of aero downforce, and a good FOD walk along the course.
Motor selection with respect to the course length was also very important of course, and the occasional failure to calculate (guess) correctly tended to result in the rather rapid and violent disassembly of the vehicle in question, often followed, depending on the course location, by an equally speedy departure from the scene of the incident. Good fun...
You know, there is a new housing development going in not too far down the road. Lots of straight, billiard table smooth asphalt...
Lessee, I know I've got some nice little wheels around here somewhere...