Building the Toyota Mirai in Japan – A Fascinating Look at Motomachi Assembly

By Steve & Tamami Laser

We were in Japan for the last Tokyo Motor Show when Toyota introduced its new FCV fuel-cell vehicle concept. The production model later became known as Mirai, which means “the future” in Japanese.


We got up-close and personal with a prototype Mirai at the Los Angeles Auto Show last fall, while the production model went on sale in Japan in December. While we’re waiting for Mirai to arrive in Toyota showrooms stateside later this year, Toyota has provided a fascinating look at how Mirai is built at the Motomachi Plant in Toyota City.


Production began at Motomachi way back in 1959. Toyota says that during its lengthy history, the manufacturing facility “played a central role in realizing the dream of Toyota founder Kiichiro Toyoda: to foster an automotive industry in Japan and benefit society at large.”


The plant started life as Japan’s first dedicated passenger car production facility. It’s been home to some of the most popular models from Toyota and later Lexus, including the Publica, Corona, Cresta, Soarer, Supra, RAV4, and the amazing Lexus LFA supercar.


The former “LFA Works” – where Toyota’s skilled takumi specialists hand-built each of the 500 series limited supercars to the highest standards – has now become the home of the Mirai, just two years since the last LFA left the factory.

This small but dedicated facility is now charged with producing the hydrogen-powered sedan with the same care and attention to detail, with an estimated three units coming off the production line every day.

Mirai Production Line – Motomachi Plant

Plant interior and parts selection: The assembly line for the Toyota Mirai is divided into three main sections: trim, chassis/fuel cell assembly, and final assembly. In each section, there are sub-assembly areas for parts installation. This video shows an overview of the production line as well as the parts selection process located close to the assembly line.

Vehicle trim: Before each Mirai body is brought to the former LFA Works assembly line, it’s painted at the mass-production line at Motomachi. The vehicle doors are then removed to enable more efficient interior work for Toyota’s takumi specialists, as well as preventing doors from being damaged. This video also showcases wire harness, dash silencer, brake fluid tank, rear combination lamp, instrument panel, main battery, roof lining, and rear bumper installation.

Chassis and fuel cell system assembly: Mirai features a CFRP (carbon fiber reinforced plastic) Stack Frame which is produced at the assembly area of Motomachi. Following the installation of the fuel cell stack, the boost converter, hydrogen tank and tubes are fitted to the vehicle. This video also shows the hydrogen leak test which is performed using helium. Next, the vehicle’s fuel cell stack and hydrogen tank are installed at the same time, followed by preparation of the electric motor and marriage of the air compressor to the fuel cell stack. Before the chassis assembly is complete, the drive shaft, front axle, inverter, water heating unit, high voltage cable, front suspension, motor, rear axle, front bumper and wheels are installed.

Final assembly: The final processes before Mirai rolls off the assembly line are the installation and assembly of the external power supply system, vehicle interior, engine bay, windshield, and rear windows. The glue used to affix the windows to the frame is 8 mm high and 12 mm wide, applied by a skilled takumi specialist at a consistent rate. This video also features the final interior trim installations, including: seats, doors, steering wheel and inverter cover. An ignition check is then performed on the vehicle before it is sent for final inspection.

Quality control and inspection: Detailed quality control and inspection is performed on Mirai before it leaves the Motomachi Plant, on its way to customers. Toyota specialists use both visual and tactile inspection to ensure the vehicle is of the highest quality and without any defect before leaving the factory.

News source, photos and production line descriptions courtesy of Toyota Motor Corp.

Story (intro commentary) ©2015