Mario Kart: Double Dash was a game in the Mario Kart series originally released in 2003. Many fans are unaware of the 2001 tech demo.
Mario Kart Double Dash apparently did not start the way it was in the final game. This 2001 tech demo was simply titled Mario Kart for Nintendo GameCube and it showed Mario and Luigi riding on a floor with Mario Kart written all over. The design for Mario and Luigi looks very identical to Super Smash Bros: Melee. Only an 8 second clip has surfaced and no more information on this tech demo is available online.