Hybrid and alternative fuel vehicles.

I'd put ethanol right off the table, it's simply not viable without props and hasn't even been shown to produce more net energy than it costs to harvest. Sugar cane and other crops are much better, as well as some groups of plankton, but it's still not a great solution because then fuel crops replace food crops, and food prices rise.

I wouldn't leave ethanol out entirely, if limited to commercial use and means of long distance traveling couldn't that make bio-fuels a little more practicle?