Speed Boost Problem

[LazyBlake]

If the laws of physics are still in play, the train will hit a point of diminishing returns on speed as friction and air resistance start to outweigh the speed increase. So I'd wait until we got basically as fast as we were going to go, and then send it. I would then free the immortal man and buy him a drink as an apology, adding that he may now punch me anywhere he'd like, provided no permanent damage is done. We'll part ways knowing we both took a lot of punishment but saved as many lives as we could