Great to hear it is almost working! 
If it is not dropping, that sounds like either the level’s physics are turned off, or the gravity setting has been changed… Check in your “Project settings” under the Physics tab that the gravity setting is set to the default (-980.0), and also click the “World Settings” button on the toolbar and ensure the first two options under config are checked, and under Physics, make sure “Override world gravity” is unchecked.
Don’t know if anyone else can think of any other reasons for that if that doesn’t work… You could also try creating a box large enough to drive on, and moving the player start over top of it to make sure it is not an with the landscape as well, just to test.
*Edit - GeoDav is probably right here, try scaling and moving the box in the physics asset first.