So, I know you can ride on top of either of the existing types of train cars. But I have a problem with being knocked off as I have sections of my train that are more like a subway. I think it would be convenient to have a passenger car to ride inside of that had windows and an interior display showing the next stop.
I also think having a sit emote would be useful both in this context and just as a general addition to the game. The menu shows someone sitting so I've always thought it was weird there's no way to sit.