Practical hydrogen powered vehicles are something that most geeks would love to see within our lifetimes ... and preferably much sooner. BMW's Hydrogen 7 series offers a glimpse of that future with a gas/hydrogen hybrid that puts a hydrogen fuel tank (actual liquid hydrogen, not fuel cells) and allows the drive to switch between gas and hydrogen at the bush of a button. Wired test drove one of the Hydrogen 7's in Germany and offers its insights into the prototype including the good (very low emissions that are mostly water vapor), the not-so-good (the eventual boiling off of the hydrogen over the course of 10-12 days) and the potentially nervewracking (refueling said hydrogen fuel tank).