Hydrogen powered vehicles are not a new concept.Automakers such as General Motors, Hyundai, Toyota, and Honda have developed hydrogen cars that get better mileage than battery-powered vehicles and similar mileage to more efficient gas-powered vehicles."The flight was essentially a performance test in the worst conditions: temperatures dropping below zero degrees Celsius, winds gusting to 20 knots and relatively little solar energy as we approached the solar solstice on December 21," said Dr.Richard Stroman, Ph.D..D., and a mechanical engineer with an NRL."Nonetheless, the Hybrid Tiger performed well."They recently completed an evaluation of a prototype at the Naval Surface Warfare Center in Carderock, Maryland.