This sounds like a 4 wheel HPV powered by both arms and legs. I dont think you will get more continuous power than using just the legs, because of the limit in the rate of taking oxygen into the blood. That oxygen intake rate will more or less match the power output of the legs. Using power from both arms and legs (and even by blinking the eyelids and nodding the head etc) might give higher performance for short bursts. The additional drive system components and 4 wheels will up the weight significantly. If you have thought a way around all this I would like to see.