There have been 4 wheel/wheel chair hybrids for people racing downhill in the past. Downhill is the ONLY thing that cart would be good for. With those wide tires, and weighing in at 50kg, it would be a serious workout just cruising flat, smooth terrain.

Would be WAAAAYYY more fun with a 250cc 2-stroke engine on it. <img src="/forums/images/graemlins/smile.gif" alt="" />