One Cycle - That's even better.

I don't know much about rotary engine design, but the thermodynamics are the same as a four stroke piston engine. I believe there were some early issues with the seals, but I guess they work well now. I suspect they are better for performance than efficiency, but I don't really know. I'm also surprised they have not caught on more.

I'm still waiting to see diesel hybrids, with a small, high efficiency, constant speed diesel running a generator; a battery bank for storage; and a variable speed electric drive system. Simple technology, but the weight and/or cost must still be prohibitive. Maybe fuel prices will start to make things like this more attractive. I hope there is some silver lining to the oil price increase.