Don’t expect Prius levels of market penetration, though. With production limited to just 700 cars this year, Toyota says initial volumes will be restricted to just 12 in the UK, followed by a further 18 next year.
The starting point for the Mirai is the Prius Plus. The two cars share the same high-strength steel platform, MacPherson strut front and double wishbone rear suspension and 2780mm wheelbase.
With exaggerated exterior styling elements, including two large air ducts that dominate the front end, it certainly looks distinctive. It’s fairly big, too, at 4890mm long, 1815mm wide and 1535mm high. Without the need to package hot exhausts within the underbody, Toyota has provided the Mirai with a flat undertray. But with a drag co-efficient of just 0.29, its aerodynamic efficiency lags behind that of the competition.
The Mirai uses a single electric motor delivering 152bhp and 208lb ft. It is essentially the same unit used in the Lexus 450h and is mounted transversely in the engine bay along with the power control electronics, where it provides drive to the front wheels via a fixed-ratio gearbox.
The fuel cell stack, which uses a combination of oxygen captured from the air and hydrogen to create the electricity used to power the electric motor, is mounted underneath the front seats. Produced in-house at Toyota, it is claimed to possess a specific output of 2.0kW/kg – a 50% improvement in the electrical energy-producing efficiency of Toyota’s initial fuel cell stack revealed in 2008.
Key to the high efficiency is a patented 3D cell design which is claimed to clear waste water away from the surface of the electrode faster than previous cell designs achieved. As such, there is an improved flow of oxygen to the catalyst layer and an increased production of electricity.
The fuel cell stack, which is housed in a titanium case and weighs just 57kg, can operate in temperatures as low as -30deg C. It is also claimed to possess a similar lifespan as a conventional internal combustion engine. Toyota expects it to provide up to 300,000 miles of motoring before it requires overhauling.
Two separate carbonfibre and glassfibre tanks are used to store the hydrogen – one mounted under the front seat and the other behind the rear seats. Together they provide a combined capacity of 122.4 litres, which is enough to allow the Mirai to provide a claimed range of more than 400 miles. Refilling the tanks takes three to five minutes.
The relatively small 1.6kWh nickel-metal hydride battery used to store electrical energy recuperated on the run and produced by the fuel cell stack sits above the second hydrogen tank at the rear.
What's it like?
The striking exterior styling carries over to the interior, which features a modern-looking dashboard with two TFT displays – one under the windscreen housing the speedo and power display functions, and another touchscreen device atop the centre console for infotainment. Elsewhere sits some less contemporary-looking switchgear sourced from various Toyota models.
The quality throughout the spacious cabin is similar to that of the outgoing third-generation Prius, with a variety of hard and soft-touch plastics as well as some less than dazzling graphics. It all feels solidly built, if a little cheap given the high price. With the fuel cell stack sited underneath the front seats, you sit rather high, although this affords good vision to each corner, making the Mirai easy to manoeuvre.
The long wheelbase provides plenty of room leg room in the rear seats, although it’s a strict four-seater, while boot space is limited to 361 litres by the battery and second hydrogen fuel tank behind the rear seat backs.
Given the complexity of the technology at play, the Mirai is extraordinarily straightforward to drive. As with the latest breed of electric cars, you press the start button, draw the stubby gear lever into drive and set off with a light nudge of the accelerator pedal.
Progress is ultra-smooth and, apart from a faint synthetically generated whine from the speakers under load, all but silent. Despite tipping the scales at 1850kg, step-off is quite brisk, making the Mirai well suited to stop/start city traffic. However, the performance quickly levels off, providing a claimed 0-62mph time of 9.6sec and top speed of just 111mph.
By sighting most of the heavy elements low down in its structure, the Mirai has greater agility and poise than you might expect. The ride is much improved over the Prius's, being more supple, smoother and with better body control. Bumps in the road don't disturb the smooth driving experience as much as they do its hybrid sibling.
The steering is rather devoid of feedback but is quite direct in response and the chassis possess sufficient damping control to provide progressive body movements when you thread the new saloon along more challenging roads.
Unexpectedly, it also rides quite well on changeable UK road surfaces. There’s good small bump absorption around town and it copes with larger surface irregularities with greater authority than the Prius.
Toyota considers fuel cell technology to be more suited to larger cars required to run longer distances rather than urban-based runabouts, which it says are better suited to existing plug-in hybrid technology.
This is reflected in the Mirai's on-road characteristics. With double-glazing on the side windows and a noise-reducing device that helps to cancel tyre roar, the Mirai isolates its occupants from wind and road noise well. Thanks to this excellent refinement and the elastic nature of its power delivery, the new four-seater is genuinely relaxing to operate.
What it lacks, though, is its own intrinsic character. Like most electrically propelled cars, the new Toyota proves a little too one-dimensional to really elicit any excitement on the part of the driver. It is highly competent, no doubt, but not the sort of car you are likely to be itching to drive simply for the sake of it. Still, with its only emission being water, the Mirai makes a bold environmental statement that many will be keen to pursue.
Should I buy one?
The Mirai is a breakthrough achievement – one that is sure to influence the way rival car makers set about mapping out their electric car future. It delivers all the environmentally friendly advantages of a battery-powered car without the need to plug into mains power for extended periods. That said, the hydrogen infrastructure in the UK is limited.
As with the original Prius, it is going to appeal to both early adopters and businesses seeking to provide themselves with an eco-friendly image. But with initial volumes severely limited, it is going to remain a rare showcase of Toyota’s fuel cell technology.
Location Buckinghamshire; On sale Now; Price £66,000; Engine Electric motor, hydrogen fuel cell; Power 152bhp; Torque 208lb ft; Kerb weight 1850kg; Gearbox Single-speed fixed ratio; 0-62mph 9.6sec; Top speed 111mph; Economy 0.76kg hydrogen/62 miles (combined); CO2/tax band na