David Jaffe's a...unique figure within the games industry. Dude loves to say what's on his mind. And as with anyone who speaks their mind freely, sometimes it gets him into trouble. Other times, though, it just results in good times. This is one of those times. From an interview with Wired's Chris Kohler:
Kohler: Apparently when Miyamoto first went to Retro Studios, they were making a car combat game, he said, "Why would you make that? Why would you put a gun on a car?" And they stopped development on the game. So maybe you should answer that question. Why would you put a gun on a car?
Jaffe: You know, honestly, I've been too busy recently trying to figure out why the fuck go-karts shoot banana peels.
Interview: David Jaffe Talks Twisted Metal [Wired]