Orders were submitted by dealers - either "Sold" orders (where a customer had ordered the car and placed a deposit), or "Stock" orders (where the dealership ordered the car for their inventory). In the 60's, less than 10% of cars were ordered by customers - 90% of customers picked a car from the dealer's stock. Today it's even less - only about 5% of customers actually sit down, order the car they want, and wait for it to be built and delivered. Each dealer was on his own in terms of what he ordered, and the ones who guessed best what would move in their region had the fastest turnover, which reduced their wholesale financing costs; the longer an inventory unit sat on the lot, the more the dealer had to pay in wholesale financing interest ("floorplan" costs).