I don't think it is fair to say the OP is a bad driver. He says he has track experience and has left the Challenger behind on the track, presumably due to the turns. Here, he raced from 30 mph all the way through 3rd gear and into 4th gear. I'll guesstimate 30-100 mph, and the Charger was 10 feet off his bumper. That length of run does away with the explanation that it was a brief race in which the weak but long and steady torque M3 was caught off guard and the strong but short and mountain-like torque Charger had the advantage.
Maybe the Charger was modified? Maybe the E9x M3 with 6MT is not usually as fast as the fastest magazine times/speeds.