Actually DY, FCV is a good transition as it will run on petrochemicals though the emissions are not as clean as if it is on hydrogen(though still cleaner than the cleanest hybrid). You're actually hitting apon the "not readily available" part of my earlier post. There are very few hydrogen refueling locations.
"I would rather be exposed to the inconveniences attending too much liberty than to those attending too small a degree of it." Thomas Jefferson