http://www.hydrogennow.org/Facts/FAQs.htm#1

(My new faqt is that since hydrogen can burn as gas in a car's engine,
according to Europeans without any adjustment, then since burning
energy is more powerful, there is sufficient power for extracting
hydrogen out of air for the engine, say for a car. The car can extract
water even in the driest sahara out of the air using air-conditioning
waste (H2O). My air conditioner in dry Colorado extracted 1.2 liters
of water from the air in one minute. Electrolysis produces bubbles
in water using electricity instantly as H and O atoms separate from
electricity. What I envision is that a car needs a more powerful
battery,
a more powerful air conditioning system and a powerful electrolysis
module. A little or no gas tank is needed, only water needs to be
kept at a level for electrolysis. The hydrogen gas is produced and
can run directly to the engine.

Starting up the car, the battery's electrolysis fills the engine with
hydrogen gas and the car can start.)