If pure water from a car is the goal the best source would be water from a fuel cell powered vehicle. FCVs produce electricity and pure water whenever the vehicle is running.

http://www.toyota-global.com/innovation/environmental_technology/fuelcell_vehicle/

Toyota, Honda, Hyundai and BMW are still working on fuel cell vehicles as well as complete hydrogen "ecosystems". Toyota and BMW have been producing hydrogen using electricity from windmills, a good way to store wind power and provide fuel for FCVs.