Not quite sure what your asking here? If I assume the simplest first, yes… you just create an index.htm (or index.php/index.asp if you are using server side code). The server will default to this file when it accesses that folder.
Not always. Some cases it tries to look for a file called “cars” for example. The end slash ensures its a directory and to look for a default file like index.html or index.php …
Strange… I’ve never seen that b4… if you find an example or have one set up then I’d like to see it… just cause I’ve never seen it b4. Almost sounds like it’s a server side issue if that’s to happen.