First Look at a Technological Tour de Force – Toyota Gen 2 Mirai Fuel-Cell Electric Sedan, $9000 Cheaper vs Gen 1

The resulting air released from the FC system is cleaner than the intake air.

With a switch to the Lexus LS400 platform, a price cut of -$9000 less with a MSRP of $49,500, and up to $15,000 of Hydrogen Fuel included with a Mirai purchase or lease, the technology tour de force sedan is poised to be a dream for US buyers and a nightmare for German and Korean automakers.

In short, the streak continues. The 2016-2020 Mirai was the first production fuel-cell electric vehicle (FCEV) offered for sale to retail customers in North America. Now, for 2021 Toyota has re-positioned the Mirai as a premium rear-wheel drive luxury FCEV with space age technology, with claims (unverified here) of a more engaging driving performance and a significantly longer EPA-estimated range rating of 402 miles. AutoInformed opines – a technological tour de force – NASA levels of man-on-the-moon magic at a down to earth price. Think of it a cordless EV.

Built on the rear-wheel drive GA-L platform that is also used on the larger Lexus LS sedan, the 2021 Toyota Mirai leaves behind its  front-wheel drive first-generation version. The body is lower, longer, and wider, with standard 19-inch alloy wheels.

A more powerful fuel cell system is claimed. The rear-wheel drive layout and four-wheel independent suspension are said to deliver a sports-luxury sedan driving feel, with more agility than before via  a more comfortable ride. The RWD layout also allowed for increased hydrogen storage to boost EPA-estimated range to 402 miles (Mirai XLE grade), a 30% increase over the first-generation Mirai despite a curb weight of, gulp, 4255 pounds or 176 pounds more. Weight distribution improves to near 50:50%, and the center of gravity is lower. Driver-assist technology includes Full Speed Dynamic Radar Cruise Control, automatic emergency braking, and Lane Keep Assist. In addition, Blind Spot Monitor with Rear Cross Traffic Alert is standard on the 2021 Mirai.

A technological tour de force – NASA levels of man-on-the-moon magic at a down to earth price.

Coming right to the point, Gen 2 Mirai has an advanced fuel cell system. Still 650 volts as in the first Mirai, the next-generation fuel cell stack is ~20% smaller and 50% lighter than the previous stack. The new, smaller stack allowed the switch to rear-wheel drive. In comparison, the first-gen Mirai was FWD, and the larger stack was placed under a raised section of the passenger compartment floor.

A compact, lightweight power control unit is now within the FC stack case, further reducing overall system size. Toyota says that relocating the air intake manifold and optimizing the gas channel separator electrodes and seals has resulted in a 12% increase in power output compared to the first-gen stack (128kw, up from 114kw). That means 182 hp and 221 lb.-ft. of torque vs. 151 hp and 247 lb.-ft for Gen 1 Mirai.

Toyota long a hold-out with NiMH batteries is now fully committed to lithium ion models.

In the 2021 Mirai, a lithium-ion battery is smaller and lighter (98.3 lb. vs. 103.4 lb.) and has higher capacity than the nickel metal-hydride battery used in the first-gen model (310.8v and 4.0 Ah, compared to 244.8v and 6.5 Ah in the earlier car). The more compact battery package fits between the rear seat and trunk, and the trunk can carry 2 or 3 golf bags. Cooling air for the battery is drawn from the cabin.

The compressed hydrogen fuel is stored in three 10,000-psi carbon-fiber-reinforced high-pressure tanks: one mounted longitudinally in the center of the car; another mounted transversely under the rear seat, and a third below the battery. The three tanks together hold about 11 pounds of hydrogen.

Mirai is a “plug-less” electric vehicle with no requisite battery charging, which can take several hours in an EV even with fast charging. Instead, the FCEV driver fills the tank with hydrogen in about five minutes, just as you do every so often with your gasoline or heaven forfend dirty diesel vehicle.

With an FCEV, the fuel is non-toxic, compressed hydrogen gas rather than liquid gasoline. An FCEV generates its own electricity onboard from hydrogen, with water as the only emission. A fuel cell “stack” combines the stored hydrogen with oxygen from the air, and a chemical reaction that produces electric current, and water, which drops out of a hidden vent pipe beneath the car.

The fuel cell is composed of an anode, a cathode, and an electrolyte membrane. Hydrogen is passed through the anode, and oxygen through the cathode. The hydrogen molecules are split into electrons and protons. As protons pass through the electrolyte membrane, electrons go through a circuit, generating an electric current. At the cathode, the protons, electrons, and oxygen combine to produce water molecules. There are no other byproducts.

The excess electricity generated by the Mirai’s fuel cell and by regenerative braking is stored in a lithium-ion battery. As a result, pressing the accelerator pedal yields immediate flow of electric power jointly from the fuel cell and battery to the rear-mounted AC synchronous electric motor, which drives the rear wheels through a fixed gear ratio.

There’s no combustion in an FCEV, that’s the whole planet saving point, but there is a kind of supercharger. An electric air compressor pressurizes the intake air, and a water-cooled intercooler reduces the temperature of the compressed air before it enters the FC stack. A water-cooled oil cooler integrated with the air compressor helps to provide reliability it’s said.

The intake system is designed to mitigate noise, which will be virtually unnoticeable it’s claimed but certainly keeping with the original German-butt kicking LS400. The inlet design and sound-absorbing material in the air cleaner prevent air column resonance. By necessity, the intake air for the fuel cell must be purified; the electret air cleaner element captures ultra-fine particles (PM 2.5), and a charcoal filter removes chemical substances. The resulting air released from the system is cleaner than the intake air.