To put this in prospective, the most powerful diesel locomotive ever built was just under 7000 HP (4.92 Mega Watts)
http://en.wikipedia.org/wiki/EMD_DDA40X (The most powerful locomotives of any kind were electric powered from an overhead high voltage line, they did NOT produce their own power and had a tractive force of about 10,000 HP.)
So unless you've got "Mr. Fusion" there is NO WAY you are going to generate that kind of power from any known fuel or battery for more than a few seconds. Tezuka wasn't an engineer, but he had a clue about that. At the time he created Atom, the only thing remotely powerful enough would be Atomic Energy (the Japanese found out FIRST HAND about that being on the receiving end of it:sick
Nuclear Fusion power, if it is EVER developed would be the answer, but I don't know if a fusion power plant would ever be scaled down small enough to fit in a robot or a car. A COLD fusion device (such as Farnsworth's Fuser which once showed some promise) might be the answer.
Roddenberry had the same problem with finding a power source energetic enough to propel a starship through the light barrier (Einstein be damned!), and thought of matter-antimatter annihilation as a power source, but the size of the Warp Core required would be huge.
An even MORE powerful source of energy was postulated in the Stargate show, and also was mentioned in the Incredibles ... Zero Point Vacuum Energy. This is only pure science fiction at the moment, though the idea does seem valid in some theories about the universe.
I made use of both the cold fusion and ZPM ideas in my fan fiction.
Now as far as a sentient robot that could be mistaken for a person with some advanced abilities (in eyesight, hearing, mental abilities, agility and strength over a human) I think that IS possible. But not to the extent of being able to bench press Locomotives and fly at Mach speeds (probably not flight at all). IOW, Hymie or Data might be possible today or within a few years. Let's take baby steps here folks.......