Thread:RR3 Michael P/@comment-29822143-20161229140852/@comment-27945602-20161229142614

Again, only when you buy the car with GiN or earn it via Special Event can you unlock the bonus series. That is you have to buy one of the car in the series (P1 or Vulcan or Porsche 2015) to unlock the bonus series. So it's all up to Firemonkey. If they don't offer GiN, you have to buy McLaren F1 or buy Vulcan (to unlock P1 GTR on Hi-Tech Legend).

Or you can use bug to unlock the series.