Whenever I load a building in skyscrapersim 1.11 alpha with vehicles loaded, they despawn whenever I walk away. I have also discovered that those cars actually go through the ground and then keep falling endlessly. In this case the collision detection with the cars would have to be fixed. If this is fixed then I definitely will appreciate it.
If this is fixed then the devs could also expand on the car class such as adding in engines or extra parts.
Thanks!