Well, it's fun kicking the snot out of new cars with a 70's car. The AZ-1 is from Mazda, it also comes in two flavors: The Mazdaspeed A-Spec AZ-1, and the regular AZ-1. The A-Spec looks like a miniature Ferrari F40, but provides no extra power compared to the stock one.
The Subaru 360, at 142hp and 861 pounds, is quite nimble. Try beating the other cars in the Compact Car Cup races...you'll be surprised how competitve those races can be. Sure the prizes stink, but it's good racing.
The '97 Skyline GT-R 4-door is kind of rare. I think it's better than the yellow Nismo four-door you win at the Luxury Car event at the High Speed Ring.
I'm not saying you have to buy any of these rare cars. Some people have fun with GT2 and never bother with the Manufacturer's Events. I can understand; about only a third of those races are worth doing.
But there are some nice cars that I would have overlooked. I would have would have passed over the Saxo, the Delta S4, and the Capucino if not for those events. Still, there were others like the SVX and the Midget that I couldn't wait to get rid of.