When/Where you bought it? From FastSpring (The store we used before the Steam Early Access release) or Humble Bundle? Also, if it is 0.4.2.2 you should have it, no matter what. Go to: BeamNGInstallation/content/vehicles. Do you have a SBR.zip there?
And you downloaded it via the ZIP or used the Steam Key? If ZIP, are you sure you downloaded the new ZIP (You have to, at each update, because that's how the ZIP work You can double check the game version by checking the window title.
Not to jump to conclusions but... Is it pirated? If so, consider purchasing it from the Humble Bundle or FastSpring to get updates the moment they go live. BeamNG is constantly being improved and it's supporting developers make more as well. Is it purchased? Try reinstalling (on Steam), as it'll download the latest version.