Right now they work similar to the tardis in Dr Who. They look smaller from the outside than they do from the inside. If you look through a window, or a hole in the wall, you cant necessarily tell how big the next carriage is, only from looking directly into it through the door can you get a sense for its size. This is pretty much limited to width, not length as you wouldn't tell the length by looking through a window anyway.
A few things worth noting here.
1 - There are bugs with how it currently works and sometimes walls /roof are visible when they shouldn't be or objects / items in the room. This is also why the floor disappears sometimes although somewhat rarely. I've been looking for that bug for over a week now, hopefully I find it soon!!!
2- I have built some features I am yet to release that will make carriages turn into themselves and walk back on itself. However, I have put this on pause as the feedback I am getting from the community is focus on the looting, & enemies first.
What do you think? Should i be prioritizing non-euclidean spaces?