The article discusses converting an old car engine to run on hydrogen fuel cells to reduce emissions. The researchers studied how a fuel cell-powered motor in a Maruti 800 car chassis compares to a regular engine. They used math to figure out the best components for the fuel cell system to be efficient at different speeds and road slopes. The study shows that fuel cell vehicles can store more energy in less space than electric cars and can be a good alternative to traditional engines for reducing pollution.