Back to the question, it depends on the crowd around.
If there are plenty of peeps around, scream at the top of your lungs "*****(insert appropriate racial slur here) IS STEALING MY **** CAR!!! CALL THE COPS!!!

1. Thief is probably leaving quickly, without your stuff.
2. You now have plent-o-witnesses-you might want to skip the racial thing, or your car may be the least of your problems.
3. Hey, u can still run.

carjacking: should: they get my empty tank gas guzzler. Maybe the cops recover it with some gas in the sob.
would: who knows, pissed off country boys do stupid shit.

for the (insurance) record: it had a full tank of gas, monster stereo and not a scratch on it! he he he