No, the only version you could possibly change it to is the 0.4.0.6ish version in the game preferences menu. (Because of DX11)
BeamNG IS still in alpha. There's no way I can find to do that, even in Steam when you right click on properties.
I still have the first beamng launcher (0.3.0), the one from 2013, but the Word pass don't seems to work with it :/ I think you can't use this version anymore, but if you really REALLY want to have it, you can prehaps try to get a "Cracked/illegal" version since you've buy the game.
Only thing that would work is the original techdemo, still have a link to that. http://www.mediafire.com/download/9yx3cnugnpe1u7j/BeamNG+Techdemo+v1.zip