There is a fuel-cell car currently being leased to consumers in southern California. It's the Honda Clarity but also MB was said to have a fuel-cell car for the U.S. market in 2010.
Now the fuel-cell car fuels with hydrogen, takes oxygen out of the air, produces electricity, runs an electric motor, and sends water out the tailpipe. And the advantage of the fuel-cell vehicle over the plug- in electric-vehicle is that the fuel-cell car has easier fueling, lighter vehicle weight, a lower cost of battery replacement, and a longer travel range.
There are a couple of things to know about the fuel-cell car. The first is that there are a limited number of hydrogen fueling stations. I see them, among other places, in southern California, in NYC, and in Orlando. The second thing to know is that the fuel-cell car has a 5000 psi tank for the compressed hydrogen. And so the hydrogen tank has to be very strong and is probably made out of carbon fiber with an outer protective steel shell.
But the strength of the hydrogen tank leads to a structural idea. Use two hydrogen tanks, one in the front and one in the back. Then have the tanks as lateral stressed members of the vehicle frame to produce vehicle strength without added weight.
Of course physicists are working on balls of carbon that store hydrogen without it being compressed so the day might come when very strong hydrogen tanks are not needed.
Now I included this post to a civil engineering newsgroup because civil engineers sometimes work in aircraft structure positions and certainly can work with bridge structures.