New Toyota Mirai: the hydrogen car, getting closer

Of all the figures Toyota gives in the presentation of the second generation of the Mirai, the one that catches our attention the least is the forecast to multiply by 10 the worldwide sales of its hydrogen car in the coming years. First, because very few have been sold to date.

Second, because the progress is so notable that reaching that goal should not be very difficult. At least in those areas where it is possible to refuel with hydrogen, which is what this technology still lacks before we start to see more and more manufacturers joining the bandwagon.

More powerful and with more range

For this new generation of the Mirai, which succeeds the model Toyota presented in 2014, a much more attractive design has been adopted. Beneath the saloon bodywork with coupé styling lies Toyota’s modular GA-L platform, with the fuel cell stack now positioned where the engine would be in a combustion car. This is a car almost 5 metres (4,975) long, whose body height is reduced by 6.5 cm, and which has a wheelbase of 2.92 metres.

The fuel cell has been redesigned for greater efficiency, which allows a range of up to 650 km to be announced, thanks to the higher power of the stack, the improved aerodynamic coefficient and the greater capacity of the hydrogen storage tanks. That is 30% more range than the previous generation, which is quite a leap.

The hydrogen is stored at high pressure in three cylindrical tanks arranged in a T shape, one running lengthwise under the floor and the other two on the sides under the seats. They total 5.6 kg of hydrogen, compared with the 4.6 kg the previous Mirai could refuel in its two tanks. Moreover, they are placed lower, which has allowed the centre of gravity to be lowered. The three tanks, filled with hydrogen, weigh around 100 kg in total.

With the fuel cell at the front, the tanks centred, and the high-voltage battery and electric motor on the rear axle, the weight distribution is 50:50.

The secret of the Mirai: the new fuel cell

Although it seemed there was little room left for evolution, Toyota has once again surprised with the new generation of solid polymer fuel cell. Not only is it more compact, with 330 cells instead of 370. It also offers higher energy density, rising from 3.5 to 5.4 kWh/litre. This allows its output to increase from 114 to 128 kW.

The total weight of the stack assembly has been reduced by no less than 50%, despite a 12% increase in power. Improvements in low-temperature performance are also announced, guaranteeing start-up and operation at -30 degrees Celsius.

Another advance the previous Mirai was crying out for is the replacement of the nickel-metal hydride high-voltage battery with a lithium-ion one. The new battery is smaller, which allows it to be placed behind the rear seats, freeing up boot space. It has 84 cells, a voltage of 310 V and a capacity of 6.5 Ah.

With all these changes and the new platform, which uses multi-link suspension on both axles, the Mirai promises much greater stability and agility than the outgoing model.

Gallery of images of the new Toyota Mirai