The fuel-cell powered Mirai gives us an advance look at the potential future of the automobile.
Words and photos by Clare Dear
In the Japanese language, the word “mirai” means future, and Toyota is taking a step in the direction some pundits predict the automotive industry will be heading in the near future – hydrogen fuel cell vehicles. The Toyota Mirai is not a concept – it’s the real deal. It’s in production and it’s the first hydrogen fuel cell vehicle that’s being sold outright to consumers. (The Hyundai Tucson fuel cell-powered crossover and Honda’s FCX Clarity sedan are only being offered on a lease basis.) It’s already in the marketplace in California, Japan and some European countries and it made its Canadian debut last week as part of the 2016 AJAC EcoRun, a showcase of the latest fuel-efficient and emission-reducing technologies.
I had an opportunity to drive the Mirai during a leg of EcoRun from Belleville to Kingston and was definitely impressed. Its ride was certainly decent, the steering responsive and the feel of the regenerative braking system was fine – it didn’t feel any different than a conventionally powered Toyota sedan, with one significant exception. The Mirai was amazingly quiet. Aside from the barely audible hums and hisses of numerous compressors and pumps located throughout the car, the most noticeable sound was simple the rush of chilled air coming out the vents to cool the cabin. Impressive, indeed.
Rather than using a gasoline hybrid configuration or a large rechargeable battery pack, the Mirai’s propulsion system is simple – hydrogen gas stored onboard in two tanks is mixed with outside air in a fuel cell stack to produce electricity, which is used to power the car’s electric motor. A 1.6-kWh nickel-metal hydride battery pack, similar to the one used in the Camry hybrid, is used to store electricity until it’s needed.
The system is actually quite similar to Toyota’s Synergy Drive that’s used in its current gas/electric hybrid vehicles, except the gas engine is replaced by a 100-kilowatt solid polymer electrolyte fuel stack. Each stack is comprised of 370 cells, each with a cell thickness of 1.34 millimetres and weight of 102 grams. This design results in a compact size and a high level of performance – the stack’s power output density of 3.1 kilowatts/litre is more than two times higher than Toyota’s previous fuel cell stack.
It’s also the main reason the Mirai’s driving range has been extended to about 500 kilometres between fill-ups. Electricity generation efficiency has been enhanced through the use of three-dimensional fine-mesh flow channels, which Toyota says are a world first. The flow channels are arranged in a lattice structure that enhances the dispersion of air, enabling uniform generation of electricity on cell surfaces. The Mirai has a new compact (13-litre), high-efficiency, high-capacity converter that boosts voltage generated in the fuel stack to 650 volts.
The Mirai’s 113-kilowatt electric motor generates 151 horsepower and 247 lb-ft of torque. The only emission from the process is water vapour. The system can launch this mid-size sedan (similar in size to the Camry) to 100 km/h in about nine seconds. There is no transmission; the power output is fed directly to the front wheels. As a result, overtaking moves and highway merging aren’t as immediate as a car with conventional gearbox which downshifts in response to such demands. Still, I think most drivers would find the rate of acceleration from launch, as well as passing, to be more than adequate.
As a bonus, the Mirai is available with an optional power takeoff device that enables its system to be used as a power generator in the event a power outage occurs in your home. Toyota says the Mirai is capable of powering home essentials in an average household for up to a week.
Refuelling the Mirai is a simple process – just connect the intake port to the fuelling hose. (Interestingly, the industry uses just one connection design, unlike the manufacturers of electrics and plug-in hybrids, which still can’t agree on a standardized plug for recharging.) It takes about three to five minutes to fill the twin storage tanks, a period of time similar to refilling a conventional gasoline tank. The two hydrogen tanks, which store the gas at 10,000 psi, are a three-layer structure made of carbon fibre-reinforced plastic. They have a combined mass of 87.5 kilograms and hold about five kilograms of hydrogen gas, sufficient to give the Mirai a driving range of about 500 kilometres. The tanks, with one located under the rear seat, the other behind the rear seatback, have been subjected to extensive crash testing and are designed to withstand frontal, side and rear impacts. Toyota says the tanks are five times stronger than conventional steel storage tanks.
The Mirai is more than a car with a unique propulsion system – its styling makes it stand out from the crowd of traditional four-door mid-size sedans. The exterior has been designed to be very aerodynamic, not only helping its eye appeal but also enhancing its fuel efficiency by reducing wind resistance. Its low coefficient of drag (Cd) – 0.29 – is comparable to the Prius, which is 0.25. The exterior mirrors are heated and power adjustable and the front door handles are operated by touch sensors, while 17-inch engraved alloy wheels complete the sophisticated look.
The bold, highly sculpted front end is highlighted by LED headlamps and daytime running lights that blend into a sweeping line that climbs from the nose of the car to the A-pillar. The headlamps are equipped with an automatic high-beam feature.
A band of LED lights dominates the rear fascia, just below the built-in spoiler on the trunk lid, which opens with a touch of a sensor button. Large, bold tail light assemblies accent the rear corners of sleek body.
The interior of the Mirai has an abundance of amenities, including a heated, power adjustable steering wheel with built-in multifunction controls, electronic push button start with Smart Key, a premium audio system with navigation, intelligent touch controls for the audio and automatic climate controls and eight-way power adjustable, heated, SofTex front seats with power lumbar support. Acoustic noise-reducing glass has been added to the windshield and front side windows to make the roomy cabin impressively quiet.
The instrument panel strays from the conventional layout with the display readouts stacked in the centre, as in the Prius, rather than the typical positioning in front of the driver. High on the instrument panel, just below the base of the windshield, is a large, centrally positioned digital display that provides the driver with essential information, such as vehicle speed, fuel level and range. To its right is a second display that shows how the hybrid system is operating. Although I wasn’t keen on the layout at first, I quickly found the positioning to be easily readable, only having to shift my line of sight slightly from the road to the readouts.
The number of occupants in the rear seats is limited to two, due to the dividing centre armrest. The seats, however, are nicely finished in a leather-like SofTex covering and are heated for the occupants’ comfort on chilly days. I found the rear leg room and head room to be adequate for two adults.
Access to the trunk is good, although the space available is slightly limited by the hydrogen storage tank positioned behind the trunk bulkhead. Still, there’s a sufficient room for several travel bags or a load of groceries.
The Mirai has a full complement of safety features, including eight airbags, a back-up camera, blind spot monitor with rear cross traffic alert, pre-collision system, lane departure alert, dynamic radar cruise control, brake assist, Smart Stop technology and enhanced vehicle stability control. Safety features specific to the Mirai’s unique propulsion system include a hydrogen monitoring system with leak detection sensors and automatic shut-off valves on the storage tanks.
The Mirai’s hydrogen fuel cell system may be the future of the automotive industry, but there are obviously some huge hurdles to clear before such vehicles are practical. Infrastructure is the biggie, with few existing refuelling stations in this country. Even California, which typically spearheads the drive for greener alternatives, has only about 20 sites where hydrogen refuelling is available.
Still, if demand grows – and there is already movement to using H2 in some trucks, buses and forklifts, for example, availability will increase and costs will decrease. Globally, Toyota predicts we will see a significant growth in hydrogen-powered vehicles by 2020 and with it, hydrogen production and availability will ramp up as well.
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