Maybe it's just me, but seeing someone play Dixie Cup Pong just sounds boring, even with a car on the line. I've played and watched my fair share of Beer Pong games, but I can't sense any tension from it there.
It might just need a little more risk. If the layout is 1 cup on the top and bottom rows, 2 on the second and fourth, and 3 in the middle, I suggest the middle row be 2 penalty cups and 1 car, and the other cups are cash (say $500 on rows 1 and 5, $1,000 on 2 and 4). You get 4 tosses, with the caveat that the game ends if you a) hit a penalty cup, or b) hit the same cup twice.
Not perfect, but at least it's not as anticlimactic.