User blog comment:LoveFastCars/New beginning with RR3/@comment-26070920-20171214165809

It also makes sense to keep the 20% discount when you unlock a new car open for maybe later.

If you progress to 1 event before the new car (that you don't need yet at that moment) unlocks, and leave it there, you can decide on whether to buy that car (at the 20% unlocking discount) later.