Crash Dummies is added to MAME. =)
external artwork: http://tsk-tsk.net/net/extart/tdummies.zip

[Linked Image from i.imgur.com]

The button info was wrong, it's like this:
Code
       K1         K2         K3          K4       Beta       BA
S1     --         --         Up          --        --        --
S2     --       Crash      Brake         --        --        --
S3     --        Down        --          --        --        --
S4 Accelerate    Pick        --          --        --        --
S5    Pause       --         --          --        --        --
GND    --         --         --          On        --        --
VDD    --         --         --          --       Off      Sound