Ya know....it was done that way to create the mystery. Batman is trying to create this boogeyman image for himself, and things like that,.....they add to his reputation.
Really, he probably was knocked out when Falcone was not around.
Rachel said there were fingerprints on drugs and I think the manifest as well...so, he probably did get out of the car at some point.
Thing for me is this: Bats would probably want to time it perfectly....time everything, so that it creates the situation he NEEDS. I think drugging the driver beforehand with a time orientated chemical, it might be the best move while adding the his mystery.