In Mario Kart Wii, there are three Weight Classes: Light, Medium and Heavy. Some general features are: * Light characters have high off-road (how much you are affected by grass and mud, etc, high being positive), high acceleration and somewhat low-top speed. * Medium characters are balanced. * Heavy Characters have low acceleration, low off-road and high top speed. * Light characters use small vehicles, medium characters medium vehicles, heavy characters large vehicles. Additionally, a heavier character may ram other lighter characters, making them lose speed.