The Koopa Clown Car is a helicopter-like vehicle with a large clown face on the front. In the Super Mario series, it is often used as Bowser's favored mode of transportation. It becomes large when bigger enemy rides on it, but will shrink to normal size when the enemy is defeated.
In Super Mario Maker, there is another variant of it called the Fire Koopa Clown Car. It can shoot fireballs with the "dash" and can charge by holding the "dash" button longer. Getting a Fire Flower will make the Car shoot three fireballs and a Giant Kuribo's Shoe or Stiletto will supersize the fireballs. A Fire Koopa Clown Car is highly recommended for shoot-em-ups.