I'm creating car vehicle by this guide: https://wiki.beamng.com/Introduction_to_Vehicle_Creation, but car is invisible.
It's just the default cube with default name and everything default and no materials, and the guide you are using is outdated by several years and doesn't explain anything at all. You should find a better tutorial, you won't do anything with this one. To fix this you should change the object name and add a material, none of which is explained in the guide but it's pretty basic, you can just google it.
