[bobcowan]

Another consideration is weight. Big tanks weigh a little more than a similar smaller tank. Fuel cells tend to weigh more than tanks. And fuel weighs about 6# per gallon.

I have a 22gal Fuel Safe cell. You can really only get 18 gallons in it. On a steady cruise, I can drive about 300 miles on one tank. That's about 2.5-3 hours or so. By that time, I'm ready to stop and take a break anyway.