Board Thread:Challenge Threads/@comment-2.221.26.126-20160305102151/@comment-26249703-20160305141043

The 7 hours referred to entering the last car, 7 days refers to winning it. Special Events, other than time-limited ones that start and end at the same time for everyone (Reign Supreme, The Gauntlet,...) have a last entry date that allows players to still win the car they're competing for, without stopping them short.