To be clear, Tuesday's feat didn't come close to approaching the overall land-speed record, which Green set with jet power in 1997. In 2006, Green also set the land-speed record for a diesel-powered car — 350.092 mph — at the Bonneville Salt Flats. He returned there Tuesday with the goal of beating that mark using hydrogen power, which he has called the "fuel of the future." In targeting his diesel speed, Green easily topped the previous hydrogen combustion world record of 185.5 mph. JCB signed a deal to buy green hydrogen, which is created using renewable energy but makes up a tiny fraction of global hydrogen production.