The suggestion is pretty simple. When a new Open Tour drops, instead of the previous reward car being obliterated and sent into oblivion, it isn’t.
The idea would be that, once a player finish the current Open Tour and unlock the current reward car, they are given the option to reset the tour. The tour could be reset as the same tour as the current Open Tour, or as one of the previous tours.
Either way, resetting the tour would slot in a new reward car from the pool of past reward cars that the player hasn’t unlocked yet. Completing the tour again would reward this car, and the player could reset the tour as many time as they’d like.
Once a player has unlocked all the available reward cars, then reset the tour again would provide no additional reward.