Unicorn cars?

My definition of a unicorn car is any unique car (So not just a livery) that can only be gained for a limited time. Ex. the Pringles MX-5 and Nutrigrain Ford GT are not unicorn cars, they are promotional cars, but the Charger and the other cars mentioned are all unicorns. I also consider the F and F cars to not be unicorns even though that was a time limited thing because they came in a DLC.