I just got this idea, and I don't know if it has been suggested before, but what about Tux Kart? http://tuxkart.sourceforge.net/ It's portable, and it could have 4 player Wifi infastructure mode.
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You've found an easter egg!

Jeez can you believe I made this thread 1 and a half years ago? When all that PSdonkey nonsense was going on?

I'm still wondering why nobody ever posted in this thread.