Lack of ability to control electric motor algorithms when climbing hills. (ie, battery runs out too soo, begins charging on the way up when I know I will soon have a chance to recharge it... etc.) Having a few optional controls would have cost next to nothing to implement, and it could lead to much greater efficiency in my case. However, since it's nothing but software and a couple of dollars in buttons, this pet peeve of mine is especially aggravating.