I'm assuming that's not your actual code since that is just filled with syntax errors (not including the <VehicleName>).
The number, or first argument, is a slot number. Just keep it at 0 unless you're using multiple sounds, in which case you'll want to increase it to 1 for the next sound, 2 for the next, etc. I don't know how many slots there are, so if it stops working you're out of luck.