Wikipedia
Ministocks are a class of car raced at many New Zealand speedway tracks. Ministocks are primarily youth grade but at some tracks are raced as an adult class. Ministocks are not currently a 'recognized' class in New Zealand; this means they are not able to run big championships in the North, South, and New Zealand Championships. In the youth grade drivers are aged from 12 to 16, and are taught to focus on how to handle a car on the racing track, learn racing rules and various sorts of tactics. Once the drivers are at the stage of moving up a level (this is when they reach the age of 17 they must stop racing youth Ministocks immediately), they are able to keep their existing cars and race in Adult Ministocks, or move into another class, i.e. Streetstocks, Stockcars, Superstocks, Modifieds, Midgets, Three Quarter Midgets, Saloons, Super Saloons, Production Saloons, Minisprints or Sprintcars.