CO2 Car?

When made a race car in high school I believe it was punctured with a piece of steel about the same size and shape as a typical 3” nail. This was a long time ago.

To launch a CO2 car, that means, to puncture the CO2 cartridge, you need a starter box, or a launch pod. This can be a simple, home-made, spring-loaded mechanism with a properly sized pin, or a commercially available product, like this, or computerized starter boxes used in contests.