Pinewood Derby
The Pinewood Derby, put on by Boy Scouts of America, is soap box racing in miniature. The Boy Scouts provide the basic materials in a standard kit --- a block of wood, wheels, and axles --- but the racers have full control over the design and the building of the race car. They can carve the wood in any way that they want to make the car more aerodynamic. Not only can pinewood derby cars win for being the fastest, they can also win for being the best looking, most original, best crafted or most colorful; awards given out by individual Boy Scout packs.
Go Kart Racing
Go kart racing is another way for youth to compete in racing, but this time in motorized carts on circuit tracks. Go karts also have extensive bumpers surrounding the vehicles, allowing for some safe collisions with other carts in turns on the track. Unlike soap box racers, go karts are rarely designed and built by the competitors; they are often provided by the track. Go kart racing does not have the same type of highly organized national racing association as soap box derby does.
Pocket Bike Racing
A recent development in miniature motor sports in the U.S. is pocket bike racing, which has been around for decades in Europse. Pocket bikes are very small versions of sport motorcycles, often rising no more than 2 or 3 feet off the ground. Organized racing takes place in some parts of the country for youth and adults alike. The simple engines in pocket bikes are easy to understand and fix, making them ideal for teaching young racers basic engine mechanics. They can reach speeds of 50 mph. While that's not nearly what their full-sized counterparts reach, riders sit so close to the ground they feel like they are going much faster.
Pedal Car Racing
A sport similar to soap box derby racing, but much more common in Britain than in the U.S., is pedal car racing. Like soap box cars, pedal cars are designed and built by amateur racers. Instead of being propelled by a downhill slope, pedal cars, like their name suggests, are powered by racers pedaling their cars. Pedal cars can also be multi-person vehicles, with up to as many as six drivers in one car. In Britain, the cars are driven by both youth and adults.