The cost per mile for that fuel.
I'm sure you guys saw the news this morning that Honda will be producing its FCX Clarity in the U.S. in a very limited fashion. Basically, there are going to be dozens available this year, growing to hundreds in the next several years. Widespread production waits for factors like available hydrogen fuel stations (currently there are a few in Southern California, but not many elsewhere). How long before you think this is a viable larger production technology? http://vlane.com/blogs_article/101/industry-update-honda-gives-its-new-fuel-cell-car-to-movie-stars