To the import dealers, this means that their allotment can remain nearly constant over time, sometimes over decades. The dealer knows he is going to have X number of cars arriving at the docks each month, and he also knows his dealer brethren in his region are going to be receiving Y number of cars. He will then know how many of those cars he has sold, and how many his buddy across town has sold, thus they each begin to develop strategies. On the other hand, some import dealers may begin to sit on their inventory so that as supply is diminished, toward the end of the year, and after all price hikes have been issued by the manufacturer, he becomes the only one in town with a particular make and model. He now has the equivalent of gold bullion cars, and can ask a hefty premium for them.
Manufacturers build vehicles.
Sometimes they miscalculate what the consumer wants, so inventories swell and the plant manager at the factory starts to get nervous. The first rule in the car business is never to stop the assembly line, so instead of stopping the inflow of vehicles, the factory begins to flood the sales regions. Eventually, all the spots available for a dealer to hide his dogs fill up. If you know that a dealer incentive exists, you deserve to claim it as your own. Once again, dealer incentives can be doled out by the region, and are in effect during a specific period of time.