There were 12 cars in the regular release. However, those 12 cars were made up of two different colors of 6 cars and depending on how far down the rabbit hole you want to chase this one you could technically say there were 5 cars because two of the cars were 1969 Mustangs (Boss 302 and Boss 429).
There were 12 Chase cars as well but since the Green Machine trait was a metallic green body the chase cars were exactly the same for both color variations.
Final Answer – There are 6 cars in the release with three color variations of each (2 regular and 1 chase)
Congratulation to Jon McNabb, Parttimecollector, and Kyle Soler. Thank you, everyone, for such detailed answers, they were great! Question 4 will be posted shortly, make sure to come back for a chance to win a Green Machine!