If Sam had intended to leave, he definitely wouldn't have left his things and taken the Impala. That would be like asking for double the ass kicking if Dean tracked him down, taking his baby. He did let himself drive around for a little bit, trying to clear his head before finally deciding on a place to grab a couple burgers.

After that, he headed back and was stepping through the door to their room, carrying a bag. "Dean? Got some dinner."