Hydrogen-powered JCB Hydromax hits over 400 mph to set new land speed record

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Is it a rocket car? Tearing across the Utah desert at over 400 mph (644 kph), a hydrogen-powered car has set a new land speed record.

Wing Commander Andy Green, a retired British Royal Air Force fighter pilot, just set a new world land speed record at the Bonneville Salt Flats in the JCB Hydromax vehicle. On two different runs on Aug. 11, the car went 400.623 mph (644.740 kph) and then 412.135 mph (663.267 kph), which averages out to 406.320 mph (653.909 kph).

That's the fastest that any car with a hydrogen internal combustion engine has traveled. "It was an amazing experience," Green told Space.com on Aug. 12 about his record-breaking drives.

"Anything above about 350 miles an hour [563 kph], we'd have gone away really pleased," he added. "It is performing better. It was more reliable than we expected, and it has blown away the hydrogen record. It's in every way a real thrill for all of us yesterday to see that happen."

Green is no stranger to breaking records. In 1997, he drove a jet-powered car 763.035 mph (1,227.985 kph, or Mach 1.02), setting a new land speed record while also becoming the first person to break the sound barrier on land.

About 20 years ago, Green also set the land speed record for a diesel-powered vehicle, going over 350 mph (563 kph). Until now, the fastest hydrogen-powered vehicle didn't come close to that, topping out at 303 mph (488 kph). But this new record shows the promising capability of hydrogen-powered engines on land.

The hydrogen engine doesn't produce carbon dioxide like a traditional gasoline or diesel engine does. And while it's not the most traditional car engine on Earth, hydrogen has powered some rocket engines for decades. For example, NASA's Space Launch System (SLS) launcher, which has two successful Artemis moon mission liftoffs under its belt, burns liquid hydrogen and liquid oxygen. (The SLS core stage employs RS-25 engines, which also powered NASA's now-retired space shuttle .)

The JCB Hydromax isn't exactly a rocket on wheels, but it does demonstrate an incredible technological feat. And the "rocket car" probably has more in common with an actual rocket than we might think. For example, while it's not as fast as a rocket, pushing a vehicle to its limits requires many of the same preparations.

"There is a countdown and a checklist," Green told Space.com. "And several times we've had to stop the countdown, reheat something, adjust something, restart the countdown and launch it off the start line."

However, despite its speed, hydrogen-powered engine and countdown clock, this "rocket car" isn't going to space anytime soon.

"These are built for the construction industry," Green said about the engines. "They normally kick out 74 horsepower," he added, so they put "two of them in a race car to show how tough, how adaptable [and] how capable they are."