C.
My in-laws got my son an electic powered ATV toy - it charges in the wall, etc. He LOVES it. in fact, his best friend and he ride like little bikers on it, very cute. We keep him on the sidewalk or in the backyard with it - always supervised. I would stick with an actual toy vs. a full scale three-wheeler. FYI - He knew how to steer and put in reverse immediately. Probably because of his obsession with motorcycles. However, you may be limited on space, so some other thoughts are guitar lessons at TCU or some other activity that he enjoys may be a fun alternative that also provides engagement at home with practice and teaches discipline, etc.
Whatever you get he will love. Have fun!