A Japanese inventor has developed the "world's smallest electric car" – an aluminium board with wheels that carries a passenger like a Segway and fits into a backpack (+ movie).

Kuniaki Sato's company Cocoa Motors is set to launch the new personal transportation device this autumn.

The lightweight aluminium board is approximately the size of a laptop and can carry loads of up to 120 kilograms.

Available as an indoor and outdoor version, the four-wheeled WalkCar is powered by a lithium battery and can reach speeds up to 10 kilometres (6.2 miles) per hour.

The device works similarly to the bulkier two-wheeled Segway device, with the user shifting their weight to change direction.

Stepping onto the board starts it automatically and disembarking immediately stops the motion. The device is small and light enough to pick up and pack away into a rucksack when necessary, similar to Impossible Technology's folding electric bike.

"WalkCar is the world's smallest electric car that can be mobile and put in a bag," said Cocoa Motors. "Just turn the body in the direction you want to go, you can move freely."

According to Cocoa Motors, three hours of charging provides enough power for travelling distances of up to 12 kilometres (7.4 miles).

Sato came up with the idea while studying engineering. He set up Tokyo-based Cocoa Motors in 2013 and has since developed the concept into a working prototype.

"I thought: 'What if we could just carry our transportation in our bags, wouldn't that mean we'd always have our transportation with us to ride on?' And my friend asked me to make one, since I was doing my masters in engineering specifically on electric car motor control systems," Sato told Reuters.

WalkCar is set to launch on crowdfunding website Kickstarter in October 2015, with a price tag of around 100,000 yen (£500) and shipping is expected in Spring 2016.

Last month, the "world's lightest and most compact electric bike" surpassed its crowdfunding goal in just two days.

Lexus, meanwhile, unveiled its eagerly anticipated hoverboard last week, which uses magnetic fields to carry its rider without touching the ground.