Just a few random rants of mine on the issue of oil conservation:

I know there are some compressed-air hybrids in the works... I believe ford has one that has an extra set of valves on each cylinder, turning the engine into a big compressor during coasting, followed by using the compressed air to "restart" the engine from a stop. Definitely a clever idea for a purely mechanical hybrid system.

I think this is where the greatest potential is. Plugin-hybrid diesels. Short trips can run off all electric, longer ones can use the diesel engine, with a large portion of biofuel in it.

This won't really help much with the problem of oil consumption, seeing as natural gas is predicted to peak around the same time as oil. Sooner if we were to switch a large portion of cars to run either on natural gas or hydrogen derived from it. I say we're better off using the natural gas to build clean power plants.

Ultimately, telecommuting will probably be the most significant change. In the LA area in particular, the main problem is the fact that there are too many cars. More people telecommuting would mean less overall driving, and would free up the roads so necessary driving could be done at decent speeds.