Hydrogen cars use hydrogen as their primary fuel source by breaking it down in a fuel cell to generate electricity to power the car. BMW took the initiative to create the first hydrogen fuel cell car, testing a BMW 7 series in 2015 that could accelerate from 0-60 mph in 9.5 seconds. A hydrogen fuel cell generates power by using hydrogen from a tank and oxygen from the air to produce electricity through individual fuel cells, with no emissions other than water. Hydrogen fuel cells can achieve over 50% efficiency compared to 10-20% for gas-powered cars. If adopted widely, hydrogen technology could significantly reduce fossil fuel usage and costs.