Is it possible to use Beamng-Drive to create another? http://gaming.wikia.com/wiki/Standalone_expansion_pack http://imagespaceinc.com/software.php
I think the user wanted to create a whole new game using BeamNG core as a base, like Garry's Mod or DayZ
It is not Licensed. Not sure if you have the engine copyrighted, but the licence (at least in the UK) is permission for them to use the engine.