King Harkinian owned and used a red car from 1975 to 2010, not counting parts of 2008. King Harkinian has owned it during most of YouTube Poop history, as late as the beginning of the Foreground-Background Era, and used it in multiple attempts to kill Sonic. It was probably destroyed when the king drove it off a cliff.
The car is a first-generation Ford Mustang. The King has modified it extensively over the years, adding features like an ejection seat and a propulsion system that allows it to fly. It can also handle extremely rough terrain and can even drive up trees. The King has an air freshener in the car that says "I <3 Dinner .".