Sorry to bump this but Sam I saw this and thought of you!
A Suburban? Hah!
My own knee-jerk reaction is that Bush is pushing for hydrogen because all the other solutions are too near-term and would disrupt Big-oil’s income before they all have a chance to move their money into some other investment.
My own personal favorite is the compressed air powered car (sorry Tuckerfan) which I confess is based as much upon personal preference as it is technical merit.