Toyota Mirai Review: Could hydrogen be the future of electric vehicles?

Intro, Price, Options and Verdict

Introduction

Some people seem to think that hydrogen, not pure electric vehicles should be the true answer to zero emissions transport. This appears to be because you can refuel a hydrogen car in the same way as an internal combustion one – just go to a station, fill up with fuel, and off you go. Battery electric vehicles, in contrast, require more of a lifestyle change, and a lot of people don’t like change. However, whereas all flavours of electric vehicle have been seeing massive growth in the last couple of years, fuel cell electric ones remain mostly at the conceptual stage. The most successful model worldwide is the Toyota Mirai, with nearly 11,000 sold globally. This earns the Mirai the badge of being the first mass-produced FCEV on the market.

Price and Options

The Toyota Mirai is not a cheap car. The price starts at £61,500, and there are probably some optional extras to make this even more although Toyota doesn’t list these on its website. The sample we had was fully loaded, which may well be the standard specification, since this car has clearly been given a “no expense spared” luxury treatment to show off the technology. However, when you consider that a Tesla Model 3 Performance, without full self-driving, costs less, this seems like a lot – and we’re led to believe that Toyota still loses money on every car due to the development costs of this unique powertrain. Essentially, this is a technology experiment you can actually buy.

We should spend a little time discussing how that powertrain works, and how it is fitted into the car. Toyota has distributed the various components throughout the Mirai to balance weight. Under the bonnet is an air intake, which supplies the oxygen for the system. Despite there being a cover saying “Fuel Cell” under here, this is not where the fuel cell itself is located. Instead, under the bonnet is the electric motor, which has a reasonable 154hp, and drives the front wheels only. The electrical inverter is also located here alongside sundry other electrical systems.

Beneath the rear passenger seats is one heavily armoured hydrogen container, and then behind these, before you get to the boot is another container and a 1.6kWh hour battery. Like the hybrid drivetrains in Toyota’s Prius and Lexus “h” cars, this uses Nickel Metal Hydride (NiMH) technology, not Lithium Ion. The battery is used for storing energy from regenerative braking, which can then be used to give a little extra boost when needed during acceleration. Together, the two hydrogen contains have a capacity of approximately 5kg, storing their contents at a gobsmacking 700 bar – that is 700x the pressure the atmosphere exerts at 111m above sea level. They clearly must be heavily armoured.

The star of the show, the fuel cell, sits in the middle of the car underneath the driver’s and front passenger’s seat. This is where all the action takes place. Oxygen is drawn in from the air intake at the front, hydrogen from the tanks towards the rear, and a chemical reaction takes place across a platinum membrane. This produces electricity to drive the motor, with a clean by-product of just H2O – water – which is vented out the rear where you might expect a tailpipe to be. So this car technically isn’t “zero emission”, but its one emission is entirely environmentally friendly.

In theory, one area where hydrogen should win out handsomely over batteries is weight. A single kg of hydrogen is enough for around 60 miles of range, whereas most BEVs won’t even give you a single mile of range per kg of battery. In comparison, 1kg of diesel will provide 10-15 miles of range. However, the extra heft of the fuel cell and hydrogen tanks means the Mirai still weighs 1,850kg, around the same as a Tesla Model 3 Dual Motor. Toyota will probably get the weight down as the technology develops, and you’d get economies of scale using this powertrain in a truck with much bigger hydrogen tanks. But at the moment this potential advantage of hydrogen is not being realised in the Mirai.

Design, Comfort and Storage

Exterior Design

The Mirai somehow looks like an oversized Prius while simultaneously appearing much, much nicer. The white pearlescent paint on the review car we had is extremely classy and offset well by the black and metallic elements of the trim. It’s an odd-looking car, and not exactly “pretty”, but we have to admit we like the design a lot. Despite this car coming out in 2015, it still looks decidedly futuristic, as it should considering the technology inside.

However, the wedge shape hides the fact that this is a big car. It’s 4.89m long, and to put this in perspective, that’s almost as long as a Mercedes E-class estate. It’s also tall – 1.535m, which is similar to a Nissan Leaf. You tend to forget how big this car is, though, until you try to park it, when you realise it doesn’t fit into spaces so well as you expected.

Although the key fob has the usual buttons for opening the doors, in fact you can just walk up to the car and, if you have the keys in your pocket, pull the door handle to unlock and open the car in one motion. You can also lock it again by pressing the almost invisible button towards the front of the handle. This is a nicely thought out system, with the expected automatic furling and unfurling of the wing mirrors.

Interior Comfort

The level of luxury inside the Mirai really makes us question why it’s not a Lexus. It has an extremely premium, quality feel and is packed with comfort features. There is leather everywhere, with heated front seats and a heated steering wheel. Underneath a flap in the central console is a dual cupholder, and behind that is a cubby containing a Qi charger, USB port and analog audio input port.

The rear passengers can be just as comfortable as the front ones, albeit without the seat adjustability. This is most definitely a four-seater, as there is a non-movable arm rest in the middle of the two back seats. This contains a handily capacious cubby, and individual controls for the rear heated seats. A pair of cupholders pop out from the front of this armrest. The rear passengers also have their own adjustable air vents, and although there aren’t any USB ports in the rear, there is a regular car power port, so you could use an adapter.

Front or rear, thanks to the car’s height, there’s plenty of headroom, and good legroom too. There has been some impressive thought given to a comfortable passenger experience. For example, when the driver gets in and puts their seat belt on or presses the start button, their seat will move forward to the preset position. When you turn the car off to get out, the seat will automatically slide back to make getting out easier. This is nothing to do with this car being a FCEV, but at least Toyota included the best features it could to show off the innovative drivetrain in the most favourable light.

Storage and Load Carrying

One area where the space inside the Mirai is a little meagre, however, is the boot. Although the Mirai looks like a hatchback (or, rather, fastback would be the correct term for a car this size), it’s actually a saloon, like the Tesla Model 3. You also only get a 361-litre capacity, which can’t be expanded because the hybrid system battery and hydrogen tanks are in the way, so the rear seats are fixed.

The boot is a good width, with extra space over the two rear wheels, and you could fit in a couple of decently sized suitcases. We’d imagine picking a couple up from the airport with their bags would be okay, which is one of the likely usage scenarios for this car. But this places the Mirai behind the Tesla Model 3, which does have rear seats that can be dropped. It also appears that you must use the key fob to open the boot.

In-Car Entertainment and Controls

Although the Mirai is decidedly luxurious, the switchgear and controls feel like they have come together from disparate parts bins. Some elements have traditional knobs and switches, others touch-sensitive buttons. The aircon, for example, uses the latter, but the buttons to choose between eco and power modes are physical ones. The gearstick-like handle for switching between drive, reverse, and neutral feels reassuringly familiar and is extremely logical in operation.

However, the screen on the JBL-powered head unit is small and the interface feels dated. Although audio quality is good, and there’s DAB radio, this is one area where the Mirai feels a little antiquated to the recent EVs with a wealth of LCD panels, such as the Honda e. The satnav menu system is also a bit clunky. You can search destination by postcode but finding that option takes some digging. It includes live traffic, but we weren’t entirely convinced by some of its routing options. That said, you don’t buy an innovative fuel cell car for its satnav, and we’re sure Toyota will bring this bang up to date with the new Mirai coming out next year.

The steering wheel is fairly traditional in design, with the usual array of buttons, plus separate stalks for lights, windscreen wipers and the adaptive cruise control. However, the dashboard readouts do not reside directly behind the wheel, as with most cars. Instead, there’s a thin row of LCD screens in the middle. The one on the far left shows various status icons, with a digital clock and indication of which drive mode you’re in to the right. The right-hand screen shows the speed, temperature, remaining range, and the speed limit. The screen just to the left of this provides lots of information you can scroll through, such as when power is being delivered or regenerative braking received. You can also view various types of information about fuel economy, such as a daily analysis of economy.

Performance, Running Costs, Range, and Safety

Performance and Driving

Driving the Mirai is almost exactly the same as a battery-electric vehicle. The power delivery is just as smooth and even. However, the one big difference is that there is more noise created in the process with the Mirai than a BEV, where at most you will hear a whine from the electric motor from the latter. The Mirai also produces secondary whines from the pumps delivering oxygen and hydrogen to the fuel cell. It’s not a particularly satisfying soundtrack, with a frantic tone, but apparently is nothing to worry about. The powertrain is not being over strained.

In eco mode, this car is not fast at all. In fact, it’s positively languid. Press the Power button, however, and it feels a bit sprightlier. In this mode, the Mirai will hit 60mph in 9.5 seconds, which is still not exactly gobsmacking when you consider a Renault New ZOE would probably beat it in a sprint, but around what you’d expect for an average family saloon. However, you do still get the instant torque of an EV, with the hybrid powertrain to help, so it’s possible to get off the lights faster than a lot of conventional fossil fuel cars, in a similar fashion to a BEV.

The handling is reasonable for a big car, with an adequate amount of reassurance when taking curves at speed thanks to the even weight distribution. You don’t feel quite so confident as you would in an EV with below-floor batteries and a low centre of gravity, such as the Honda e, but there’s no worrying over- or under-steer. Overall, though, this is not a driver’s car.

However, one area where the Mirai beats most other EVs we’ve reviewed so far, bar those made by Tesla, is in motorway composure. This car feels absolutely at home doing 70mph. It’s very comfortable and stable at speed. Toyota clearly intended the range of this car to be matched by its ability to transport its occupants on highways with considerable aptitude. The low drag coefficient of 0.29 helps keep consumption reasonable even at motorway speed.

Nevertheless, this is an area we seriously hope Toyota improves in the new version of the Mirai that is due in 2021. This will switch to rear-wheel drive, and Toyota is rumoured to be targeting the Tesla Model S more with this update. If it has any hope of doing so, the new Mirai will need much better performance and handling. Toyota has claimed that there will be 30% more range, so around 400 miles. The Hyundai Nexo FCEV already offers this kind of range, however.

Range and Charging

When Toyota first released the Mirai in 2015, the top Tesla Model S 70D had an EPA range of just 240 miles. In comparison, the Mirai’s 300-mile range on a full tank of hydrogen (or full tanks, as there are two of them) would have seemed like a significant improvement. It’s still pretty decent, although we reckon the real-world ability is more like 250-260 miles. The car’s range indicator seemed quite accurate during testing, sometimes even underestimating the miles left, which is highly unusual in an EV.

However, this brings us to the big reason why most consumers shouldn’t buy a hydrogen car anytime soon, at least in the UK. There are currently just 10 places where you can refill one. These are mostly arranged around London, with a couple of stations in Swindon, one in Sheffield, and one in Scotland. This means that, if you think an EV will give you “range anxiety”, try a FCEV. Unless you live near a hydrogen station, you might need to drive 30 miles just to refuel, or even 200 miles. Unlike a BEV, there’s no lowest-common-denominator option of the so-called “granny” charger plugged into a domestic 13a socket. If you run out of fuel, you will need to be towed to the nearest hydrogen spot.

Hydrogen is also not as efficient as battery-electric, and not necessarily as green as you might think too. There are currently two primary ways of making hydrogen. One is electrolysis, which is basically running a fuel cell in reverse. The refilling station will use electricity and a water supply to make hydrogen on premises, releasing the oxygen by-product into the air. This is about 80% efficient, meaning you will have lost 20% of the electricity that arrived at the refuelling station. A Lithium Ion battery, in comparison, will store about 99% of the electricity it is supplied with.

The other way to obtain hydrogen is from fossil fuel sources – natural gas, methane, and coal gasification. This does generally release CO2, although there are methods to prevent this, so it isn’t really better for the environment than petrol or diesel and definitely not zero emission. Although 95% of the hydrogen used in the world is produced in this way, most of the UK’s hydrogen refuelling stations use on-premises electrolysis, except the one at Heathrow, which has its hydrogen delivered in trucks from plants which produce it from fossil fuels.

Then, finally, there’s the energy wastage from the process of converting hydrogen back to electricity in the fuel cell itself, which is around 60% efficient, meaning you lose 40% of the energy stored in the hydrogen. So your hydrogen car is stuck between two stools. Either it’s much less electrically efficient than a BEV, losing about half of the electricity supplied if it was refuelled via electrolysis. Or it will lose only 40% but still be polluting, if the hydrogen came from fossil fuels. Either way, this doesn’t sound as eco-friendly as a battery electric vehicle.

None of this completely discounts FCEVs. If you have abundant renewable energy, the inefficiency with electrolysis and fuel cells would be less important and the easy refuelling make the technology more attractive. The lack of refuelling stations in the UK is country-specific, too – there are a lot more in Germany, for example. It also has more potential to provide really long ranges with large tanks, so is attractive for long-distance trucking or trains. But for consumer-level cars, the drawbacks compared to battery-electric make it unlikely FCEVs will miraculously take over from BEVs.

Running Costs

Another issue for FCEVs is running costs. At the moment, hydrogen seems to be pegged at a nominal £12 a kg. So it takes £60 to fill the Mirai up. That’s about six times as much as it costs to fill up a Model 3 Long Range, for a similar number of miles. So a FCEV may be similarly zero-emissions as a BEV, but it’s definitely not as cheap to run. A £60 refill for 300 miles equates to 20p a mile – no cheaper than petrol or diesel, either.

The Mirai does come with a decent five-year, 100,000-mile warranty, although we couldn’t find an insurance group for it. The car doesn’t appear to have one, but given the high price, the insurance group is likely to be high too. As a zero emissions vehicle, it will of course have zero VED and have zero benefit-in-kind (BiK) as a company car for the first year if purchased through a company. Since most of the Mirais, and indeed most FCEVs in general, are corporate buys, this is particularly important.

Safety

Although the Mirai isn’t a new design now, Toyota has packed it with safety features. You still get modern safety features like lane keep assist, blind spot detection, and a speed limit warning. The blind spot detection usefully glows an orange icon on the wing mirror itself. But some of the other warnings cause an audible “ping”, which would be fine if it was obvious what that ping meant, because it seemed to be the same noise for exceeding the speed limit, detection of a vehicle in your blind spot, and straying out of your lane. There's a radar-based adaptive cruise control, and rear-view parking camera as well as front sensors. Pre-crash sensing is built in, but this doesn't appear to include automatic emergency braking.

Key Specifications

*based on hydrogen costs of £12 per kg