You are completely wrong about the powerplant.
Do some calculations. What horsepower would be required to run a one-ton armor suit?
Unlike a one-ton car, a lot of the energy for locomotion is reciprocating energy. This being the case, like a piston engine where the piston being slowed down at the top and bottom of the stroke is actually using piston velocity to accelerate the crank, similarly, energy from a pair of running legs going back and forth, for example, can be fed back into the system. When the legs are at their maximum velocity is when they are passing each other. They then flip their acceleration vectors and begin slowing. This energy does not have to be wasted.
But, anyway, it won't take as much energy to move a one-ton suit of power armor at 40mph as it will to move a one-ton car at ITS top speed, because lower air drag, less energy to move one ton to 40mph than it takes to move a car to 120mph for example.
The power source only has to be about 135hp. I won't divulge actuation systems so a bunch of rice-gobblers can run to the patent office with it, but the power is not very great, and it will easily fit in a backpack-sized bump anywhere the design sees fit to put it, depending on whether the soldier or Marine power armor suit is going to be in a quadruped or biped configuration. Think of the gigantic 62 ton M1A1. 1500hp. How much does the engine weigh?300 pounds?
There is no problem at ALL powering these things, or actuating them. The PROBLEM is the corruption in DARPA and the US Homomilitary in general. Is anyone above first lieutenant actually in possession of a virgin anus anymore? Obama started the Pride Parade.
Nothing is more corruptible than a homosexual. Nothing.