Two and one-half stars. Rated G. 100 minutes. Lightning McQueen’s third time around the track is showing signs that Disney/Pixar’s reliable “Cars” franchise may, after two popular and original installments in the series of animated tales about talking cars, finally be starting to run out of gas. To be sure, “Cars 3,” which centers on a cocky race car named Lightning (voice of Owen Wilson) and his fears of obsolescence in the face of more high-tech competition, still has enough fuel in the tank to drive the story across the finish line.