Board Thread:Game Discussion/@comment-33575008-20171106173329/@comment-28169398-20171106221536

IamtheSpicer wrote: Since its a bonus series of Racing Spirit, which is placed under it, then yes, it will appear when Racing Spirit is unlocked albeit greyed out until it is unlocked specifically. Also, if you buy one of the LMP cars on Get-It-Now sale, it will open the Bonus Series, no matter where you are in Career.

You may be able to get into Endurance Kings if the Porsche 911 RSR (2014) or Porsche 911 RSR (2013), however intel on future sales does not show these cars on sale anytime soon....