I personally drive and love my (2003) diesel Jetta. It's big enough for 5 people and a good amount of luggage, but highly economical. I always get worse mileage in the winter due to only lower quality fuel being available (they add things to prevent it from gelling up that make it less efficient), but on my current pattern of 40 miles of city driving every day, I'm still getting about 42mpg.

The other upside is on road trips, not only do I get upwards of 50mpg, I can do a little research beforehand and find filling stations along the way that sell various blends of biodiesel. On top of that, the engine life tends to be better with a diesel. I used to know a guy with an 1981 diesel Jetta that he had never done any major engine repairs to, just routine maintenance/replacing worn out parts (ball joints, brakes, etc.), with over 700,000 miles on it.

I'm just waiting for a hybrid diesel to come out. I imagine something like that could quite easily attain over 60mpg. Hopefully they'll get this algae based biofuel thing figured out soon, so we can start mass producing that and stop using farmland for fuel.

Things I'd love to see in the future: photovoltaic paint (for recharging those crazy hybrid batteries); algae based fuel; unobtrusive wind energy (giant windmills are great, but I want something I can mount on my roof... say 1000 or so microsized turbines on the roof ridge); organics recycling programs in major cities (yard clippings taken to compost plants to create methane or burned for electricity, most of the gases from burning yard waste are useful if recaptured and refined - this one may not ever be economically feasible)