I'm not sure what you're trying to figure out but they don't make a profit until the car is sold with a margin of profit. I'm assuming you're not asking about revenue recognition rules. They certainly don't profit from a deposit especially in states where they are fully refundable. What are you trying to determine?
The dealerships are swamped with people not wanting the car but just wanting to see it. The 1,000 really is an arbitrary number to help them see interested people.