All together Achievement
Play a 4 player split screen raceTo unlock this achievement, you'll need at least three extra controllers (four total). Choose 'Play With Friends' from the main menu, and you'll need your other three controllers to sign in with at least guest accounts. The shortest track is the final Overdrive Event from Adventure Mode, and you can set it to one lap to make it even shorter. For this achievement, all you need to do is finish the race; it doesn't matter if you win or not. Once the race is over, you'll unlock this achievement.