I never replied as to whether I got a social bar boost from my Sim riding his Beast. He didn't, but then, he doesn't have the Vehicle Enthusiast Trait. Then, Verde, his Beast, got stolen, so he's starting all over with another green Beast.
You don't need VE to be friends with your vehicle or to name it, so does it just make that process faster/easier? There's nothing wrong with new vehicles and clothes to go with them, but why add a new Trait? I remain baffled.