The study compared hydrogen and gasoline-powered vehicles to see which is more efficient and emits fewer pollutants. They looked at different types of hydrogen vehicles, like ones with internal combustion engines, hybrids, and fuel cells. By using a computer model, they found that hybrid hydrogen vehicles are the most fuel-efficient, especially for driving in cities. Hybrid hydrogen cars can be just as efficient as gasoline cars. Overall, hybrid hydrogen cars are better for fuel economy than fuel cell cars. Driving in areas with low power needs is best for hybrid vehicles.