You must be new. Welcome to the forums! Just for future reference there is a vehicle siggestions thread. Please search before you post.
BeamNG cannot produce real vehicles, that requires licensing and they're on a pretty small budget. Plus, real car companies won't want their cars being damaged the way cars can be damaged in BeamNG.
Because ror is free and anyone can make any car for BeamNG as long as it isn't in the official release