Due to the way replays work at the moment you can't (the replays are recording of inputs and the physics engine works from there, and the physics engine can't work backwards).
Scawen has said he'd like to do something to fix that issue, but when is an entirely different matter altogether.
Altogether: It's an entirely different matter

illepall
minus some couple of km/h or mp/h to be more correct 
Its just a bit annoying when you have 20 cars on the grid and you have to order them manually from a list on a little piece of paper or something.