Interesting article on plug-in cars here. If these catch on, they'll have to rewire all the garages and parking lots at the condos, apartment buildings and office buildings so that each parking space has an electrical outlet, and also figure out how to charge the users for electricity. Each parking space would have to have some kind of meter on it (most likely in a computer at the electric company).
From what I've read lately, biofuels may not be feasible. The car article talks about the arable land needed for growing plants for biofuel. Why can't they build enormous, light-filled skyscrapers in rural areas in which to grow the plants? Plants don't need to grow in the ground itself and take up space. And they can also be grown hydroponically (feasible or not, I don't know). Just a thought.