Cars are dangerous moving objects from the city. If one hits a player, a life is lost. It gets even trickier because players have to get twigs and eat while they are whizzing about. Cars always appear to be a Red color. There are no cars in the wilderness.
They also appear in the Industry, but food doesn't usually spawn in the middle of the road.
Do not try to ride a car. Even if you somehow land on top, any part of the car WILL hurt you and make you spin out. Only Eagles can outrun cars while flying.