Train Karts are craftable karts that resemble steam locomotives. They have been here since the beta,. and maybe before. They need metal, fire, and the kart color of the player's choice to craft. They are very popular, as they even show up on the sign in page. However, you only encounter fire (and therefore the ability to craft the train kart) during the "squirrel quest". This kart should not be mistaken for the Engine Karts which resemble diesel locomotives instead of steam locomotives.

Blue train kart

One of the train karts


the kart kingdom sign in page. note the train kart in the right corner