A popular sport in the clan territories. Tanks come together and organize races. The rules are easy: the participants have to race each other on a specially built race track, completing a certain number of laps. Upon finishing, they are judged by the order they pass the finish line. The first few that pass the finish line are given points according to their order. Tank races can span many hours with multiple heats; at the end of the event, the tanks with the most points are awarded highly coveted prizes such as currency or valuable parts. Some events are part of a greater ongoing event - championships. Winning those grants the racer fame, and often sponsorship or recruitment by wealthy clans.
Back when tank races became a thing, they were originally used by clans to find talented scouts. Being agile and fast are sought after qualities for a scout. The competitions were used to compare the most suitable individuals. It didn't take very long however until the competitions grew to a greater scale, especially because the vehicles found them very entertaining.
The racers are divided into categories, based on their engines and weight. This is to ensure that the chances are (at least mostly) equal among participants. As tank nature tends to be, these races can be very rough. It is explicitly allowed to "bump into" other vehicles, a term that is defined vaguely and open to interpretation - usually the jury decides what constitutes as "bumping into" and "purposefully crashing into"; the latter is forbidden by the rules. A lot of vehicles break this rule on purpose. Of course they deny it and call it accidents, but many are so hellbent on winning that they risk injury and penalties.
Generally, every tank may participate in races, but most of the time, it's tanks that do it as a hobby or profession. The racers usually paint themselves in flashy colours for the events, a tradition that came up as the popularity of the sport increased. The purpose of this is to make them more easily distinguishable from each other.