This mod is developed in your own time and, as my crews leader always says: RL comes first.
So, you didn't actually mean that winning the pink slip means that you will have the car in the future? Okay, than my idea went way further then yours. Maybe you should determine a price for the car according to it's performance index, so the NPC driver, who lost his pink slip, basically can continue racing in the future but not this meet and the player wins the determined sum as the NPC basically buys his own car back?
I, just for the fun of it, turned up with a Hakuchou Drag for a meet and the script seems to have noticed the vehicle and now spawns it's own Hakuchous. I know how to remove it but it surprised me a bit, as the script doesn't seem to be able to spot the difference between car and bike. Will this then be part of the bike meets you said were planned?