I live in a community with a posted speed limit of 15 mph. I travel a full minute at 15 mph before I exit the community to a city street. My 2013 Accent Hatchback won't "glide" along at 15 mph. It jerks and surges and races and slows down. I've tried using the manual option and keeping it in 1st gear however, when I reach the 1st gear tachometer limit at 15 mph the car "stalls" and the tachometer needle drops out and the car slows to 5 mph. Any ideas?