Board Thread:Game Discussion/@comment-26547095-20150902054903/@comment-26249703-20150902191843

I think what they're worried about is balancing. New NASCAR vehicles were created with drafting in mind, whereas old events might create some problems by adding that feature in retrospectively. Unless it's lazyness or because it's such a big part of NASCAR that the organisation didn't want to not have that feature in the game for their cars.