Has this idea been up yet?
I think the game--there should be one version--should start with all the normal, buyable cars, like a Mustang or STi have always been, or even a Fiorano, and a few used cars. There should be no "classic" cars, high-end race cars (say, an R8 or JGTC cars), concept cars, or general unbuyable cars.
You could get a great start with the few hundred normal buyable cars, especially since these are usually the only cars people end up using often anyway. There would be no need to download those classic cars, high-end race cars, concept cars, or general unbuyable cars, but if you wanted the extra hundred or so of these "special" cars you could pay a very small price--maybe USD $.25-$.40--for access to these cars. You have to remember that few of these cars would actually be practicle for use, like the race cars, so only the real collectors would end up spending more than $20 on these special cars.
Now, these cars I speak of would be available to everyone. THey would not be special editions. That position would be reserved for truly rare and custom cars (in real life). These may cost a dollar or more and would be available only in limited numbers. I have no idea what sort of numbers--that's what PD's consumer surveys are used for.
Another idea is that the famous reward cars should be few and far between. These cars could be either the normal cars or the special cars--race cars and such--and you would recieve them via free download. I think the best times for these to pop up would be when you make a certain goal, like a percentage of completion. I think every 25% would be a good seperation, with the value of the car increasing every time, the F1 probably being last. I think some of these free downloads should occur for winning certain races, but only a few and only those where it might occur in real life or races that are huge milestones in the game, like an endurance race.
That's about all I have right now. What do you guys think?