Super-fast hydrogen car smashes a speed record

It looks like a yellow rocket on wheels, shoots across the ground faster than most planes take off and is powered by one of the lightest gases in the Universe.

British driver Andy Green has set a new speed record in a hydrogen-powered car.

Green, who is 64 and used to be a Royal Air Force pilot, drove JCB's Hydromax car at 406mph, or 654km/h, at the Bonneville Salt Flats in Utah in the United States.

It's the fastest a hydrogen-powered car has ever travelled.

Bonneville is a famous place for speed records because it is wide, flat and empty.

The ground is made of dried salt, creating a huge natural racetrack. Drivers need lots of space to speed up, race in a straight line and then slow down safely, so the salt flats are the perfect place.

Green is already one of the fastest drivers in history. Almost 30 years ago in 1997, he drove a jet-powered car called ThrustSSC at 763mph, or 1,228km/h.

That made him the first, and still the only, person to break the sound barrier on land.

The sound barrier is the speed sound travels through air. When something goes faster than sound, it can create a huge boom.

The hydrogen car was still a few hundred miles per hour off breaking the sound barrier, but Green said: "This record is a huge achievement by a world class team and superb technology."

The Hydromax is not shaped like an ordinary car. It is long, low and pointy, so it can slice through the air more easily.

At huge speeds, air pushes back very hard, so a smooth shape helps the car go faster.

Special fins and the car's heavy, low design help stop it lifting into the air, keeping it pressed down on the salt flats like an F1 racing car does on a track.

Hydrogen could be an alternative fuel to petrol and diesel in some vehicles.

When hydrogen is used as a fuel, it can produce fewer harmful emissions, but it is still difficult and expensive to make, store and supply, so it is not yet a simple replacement for ordinary cars.