In a demolition derby, drivers in stripped-down older cars deliberately collide inside a marked arena until only one car is still moving under its own power. Rules restrict where a car may be struck, usually protecting the driver's door, and a car that stops moving for a set count is eliminated. It is a ticketed grandstand event at many county fairs and reliably the loudest thing on the grounds.
Demolition derby
A grandstand event where drivers wreck cars until one still runs.