There was no denying that Sam was beginning to appreciate being here in Storybrooke. Adam was correct in his assumption that this dramatic change in attitude was partly due to Gretel, in no small part thanks to the spell she had tried on him. It was also because of the fact that his brothers were both here, alive and (for the most part) well. Okay, so they had some ways to go with the marks influence but after the way the spell had worked on him, Sam was hopeful it would be at least a temporary alleviating factor for Dean.
Though he'd be loathe to admit it, Ruby had definitely been right about the whole making the most of the situation thing. He'd never tell her that of course. Still, back home in his timeline of reality Dean was dead, about to become a demon and then god knows what was going to happen trying to get the mark off him. Charlie was going to be dead for one thing. Sam was happy to forego all of that for a little happiness, and a little hiatus from the monsters and the demons and the shitstorm that was their lives back home.
He'd gotten the idea for the car during a conversation about what people missed from back home. He figured Dean missed his 'baby' and he sure as hell could use something to work on constructively that might keep him occupied and not so focused on the mark. Besides that he thought it might be an opportunity for all three of the brothers to get to know each other a little better. He had wanted to know Adam ever since he'd learned he had a younger brother and he'd be damned if he was going to waste an opportunity to do that. He'd mentioned it to the kid half expecting him not to go for it, yet here they were out hunting for something to fix up. "So, do you know if there's a used car lot or a garage or anything in town?" He said, figuring Adam might have been around town a little more because of his work and his studies.