There is an app that judges your driving and can give you a "score" based on hard or smooth braking and acceleration and avoiding repeated sharp turns and whatnot. This game me an idea - Step 1) Install this app Step 2) Go to an autocross with some people Step 3) Fire up the app for each run and finish at the end so it stops recording. Step 4) Lowest score wins.

I call it Oppo-golf. You're not really playing each other, you're playing the course :)