Is there a way to import original BeamNG vehicles in blender, edit it and then paste it into the game (Not really paste, create a new vehicle)
Yerp. The way I do it is copy the BeamNG vehicle zip files you want. Extract them into new folder for editing. You can then import the Collada data (.dae) files into Blender under File>import. Getting it back into game is the same as creating any other mod. Another challenge
This may be of help if you havent already figured it out http://www.beamng.com/threads/how-to-correctly-import-export-official-vehicles-via-blender.14793/