While the Doble's four-cylinder compound engine makes only 150 horsepower, it produces a staggering 1,000 pound-feet of torque, according to Leno. That much power means that a transmission isn't necessary, and it directly drives the rear end.
For much of the video, Leno puts on his teacher's cap and explains step-by-step how the Doble's advanced steam engine works, and it's a very complicated piece of machinery, especially if your are used to internal combustion engines. One of the most interesting parts is the system's efficiency, because after being used in the engine, the gas is condensed back into water and heated again.
If you're a fan of engineering or mechanical systems, this is a fascinating video to watch, and it's amazing how functional the Doble makes steam power appear. In fact, it's almost possible to see steam as a realistic alternative to modern engines. Scroll down to watch Professor Leno give you an inside look at his idea of the pinnacle of the steam-powered automobile.