“Supernatural” fans are in for quite a ride as the popular series kicks off its fourth season Sept. 18. Actor Jim Beaver, who plays Bobby Singer, said viewers should brace themselves for even more of the unexpected. In an exclusive interview with Rabid Doll, Beaver said fans can count on “twists that folks aren’t going to be expecting at all.” Although Beaver wouldn’t elaborate too much on this season’s plotlines, he did spill the beans on one surprise that even caught him off guard. “I get to drive the Impala,” he said. “I was shocked when I saw that scene coming up!” Beaver said there’s no doubt Dean, played by Jensen Ackles, will be upset, but he’s certain forgiveness will be forthcoming. “I think Dean will forgive Bobby, because it was in the process of saving Dean’s life.” Still, the car …