the latest design that i have seen is that the engine has no pistons or mechanical parts. bascially its these electrical plates that are stacked next to each other and the hydrogen is ran across the plates to produce the power. now if you can develop a chasis that limits the amount of moving parts so that the power can be evenly spread throughout the entire mechanical system then you can achieve the power needed and prevent loss. also if you got the money an all carbon fiber chasis where everything is built in that chasis. so basically you have a steering column and gauges. Then the motor, battery and electronics are built into the chasis so that you cant see it. you might also want to think about putting individual motors in each wheel so that you dont have to worry about drivetrains, transmissions, etc. Since the wires would be tucked into the chasis base board it would make it look clean and hidden.