Currently reading: Toyota Mirai long-term test review: running costs
Toyota says the Mirai will do for the hydrogen fuel cell car what the Prius did for the hybrid. So is this really the future?
Steve Cropley Autocar
6 mins read
19 July 2017

Once they’ve established that it’s not prone to imminent explosion (if anything, hydrogen is safer to carry than petrol), the second thing people want to know about the Toyota Mirai is how fuel efficient it is.

After all, the Mirai is quite closely related to the Prius, which has economy at its core. Is the Mirai economical too?

We were keen to find a figure at the outset, but the more we thought about it, the more truth seemed to be carried in the words ‘depends how you measure it’. The easiest figure to give is miles per kilogram: the Mirai takes around 4.7kg of compressed hydrogen when the fuel gauge says it’s as near as we’re prepared to get to bone empty, at which point it has done around 270 miles. That calculation is easy: the car does 57.02 miles per kilo of hydrogen. Trouble is, this doesn’t help much, not least because compressed hydrogen is about eight times lighter than petrol.

Then we spotted a figure in the Mirai brochure stating that a tankful equates ‘roughly’ to 60 litres of conventional fuel capacity. That means 4.7kg of consumed hydrogen equates roughly to 56.4 litres, or 10.3 gallons. It gives you a range of 270 miles, thus in ‘petrol equivalent’ the Mirai returns 26.2mpg. Not impressive, if it matters.

We think a more interesting gauge of the Mirai’s efficiency is to measure fuel cost per mile and compare it with, say, a 40mpg petrol car. Hydrogen costs £9.99 per kilo, so our 4.7kg fill-up costs £47, give or take. Over 270 miles, that’s 5.74 miles per pound, or 17.4 pence per mile. Now consider a 40mpg petrol saloon fuelled at £1.20 per litre/£5.46 per gallon. Over 270 miles it would use 8.1 gallons, which costs £44.20 or 16.3p per mile, near enough.

Ergo, running a similarly sized petrol car costs roughly 90% of what we’re paying to run the Mirai.It seems a steal given that this is still very much an experimental car.


First report

It’s weird how differently people react to the promise of hydrogen fuel cell cars – such as the 3000-mile white Toyota Mirai that joined our long-term test fleet and will be around for the next six months.

When, at a recent gathering, I mentioned to a few people that my odd-looking Toyota was powered by hydrogen and would travel through its entire life without emitting a solitary atom of noxious exhaust gas, one group fastened instantly onto the relatively pedestrian fact that filling stations are rare within the London area. They dissolved into laughter and dismissed the whole idea.

The others were quite different. For them, it was as if the holy grail of perpetual motion had landed on their doorstep. The fact that this car ran on electricity generated from non-polluting hydrogen, produced from a substance as ordinary and plentiful as water – well, that was magic. Especially when you learned that the hydrogen car is actually smoother and quieter than a vehicle powered by an internal combustion engine.


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Toyota Mirai

Toyota claims another first: Europe’s first ‘ownable’ hydrogen car, whether the infrastructure to properly support it is ready for it or not

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To come clean, my sympathies are with the second group. The first motoring magazine I ever bought, 56 years ago, contained a bullish story about the potential of hydrogen fuel cells. It seemed magic then and it’s still magic now, despite the littlecelebrated fact that indoor electric fork-lift trucks have been using on-board hydrogen fuel stacks for decades to avoid filling factories with exhaust fumes. Nothing is new…

However, what really launched us at Autocar on a mission to become one of the UK’s dozen or so Mirai ‘owners’ was hearing how Toyota’s bigwigs are increasingly linking their achievements with the Prius hybrid with their dreams for today’s Mirai.

Back in 1997 the oddball Prius Mk1 appeared on the market amid a myriad of weird claims, not to mention bouncy suspension and styling not dissimilar to a potato. You’d never have seen yourself buying one. But by 2003 we were buying them, and in big numbers. Today, the world’s Prius population is closing in on 10 million and company officials are starting to talk about the Mirai’s trajectory in the same breath.

Who wouldn’t want to know more about such a car, especially one that looks so futuristic? Regular readers will know that we are already familiar with hydrogen thanks to the Hyundai ix35 Fuel Cell on our long-term test fleet, but whereas the Korean car is based on an existing model, the Mirai is all new.

Toyota marketing manager Jon Hunt, a hydrogen enthusiast whose day job is putting together big fleet deals involving more conventional Toyotas, donated one of his busy days to getting us in the loop.

Had we been able to do this for real, Hunt told us, we’d have had to part with a £61,500 purchase price, although a retail customer would more likely pay £750 per month, including fuel. And just so you know, a Mirai carries 60 litres of hydrogen compressed into its tanks at 700 bar, and when it’s full, the fuel weighs just 5kg, compared with 40kg for 60 litres of petrol.

We’ve had some Mirai experience before, but this was different. London has four hydrogen refuelling stations – Teddington, Heathrow, Hendon and Rainham – and will soon have its most commercial of all at the vast Cobham service area on the M25.

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Jon’s plan was to meet us at Autocar’s Twickenham HQ with our car and another, then take us to the nearby Teddington station and the one a little further away at Heathrow.

A Mirai is much like a Nissan Leaf to drive. Same torque from nothing. Same absence of noise (just the faint chuntering of a compressor at times). Same precise delivery of the torque you asked for. (You realise at times like this what ‘wrinkles’ there are in the power delivery of the smoothest internal combustion engine.) There is some consciousness of road noise because there’s nothing else to drown it, and the Mirai has a gently damped, very soft ride, helped by the fact that this is a 4.9m-long car that weighs close to two tonnes with a couple of occupants on board.

Refuelling is a breeze. It’s not so different from the business of filling your car with petrol, except car and pump have to bond and check one another (fuel flows at 700 bar and minus 40deg C) and you don’t have to hang onto the handle. But it’s nothing like recharging a battery car.

Neither is range anxiety much of an issue. Toyota claims a range of “up to 300 miles” for its 5kg of fuel, but we’ve not extended it that far yet, tending to leave 100 miles in the tank. But it’s steady give-and-take driving that provides the best mileage and range, where the regenerative braking system gets a chance to replenish the (smallish) propulsion battery from time to time.

In essence, though, it’s a simple, quiet, ultra-refined, gearless but very torquey car. The quietness and smoothness don’t encourage you to drive it hard, although it’ll do 111mph flat out and 0-60mph in a decent 9.6sec. The steering and stability are good, too.

For now, however, the buzz is knowing that every mile we do costs the environment nothing from our tailpipe, and that writing about the pleasure implicit in owning and driving one of these novel cars might contribute, just a bit, to their greater eventual popularity.

Price £61,500 (after £4500 gov’t grant) Price as tested £61,500 Options None Economy 50-55 miles/kg H2 (26mpg approx) Faults None Expenses None

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6 June 2017
Does anyone know how much a refill costs at one of the service stations? Steve says that £750/month includes fuel but that can't be sustainable in the medium term can it?

6 June 2017
johnfaganwilliams wrote:

Does anyone know how much a refill costs at one of the service stations? Steve says that £750/month includes fuel but that can't be sustainable in the medium term can it?

I am not sure about the figure quoted but currently, hydrogen pump prices fluctuate wildly with the mode being a few pence per mile more expensive than diesel. Rule of thumb at the moment is, you don't do it for the cost.

6 June 2017
The Hindenburg was filled with Hydrogen too...

But in all seriousness, it makes me a little nervous with that much pressurised Hydrogen on-board. Is that a valid safety concern? Has their been high-impact crash testing?

6 June 2017
The tanks are tested to a certain standard, and are designed to stop a high calibre bullet, so no worries about the tank getting punctured. If it's strong enough to hold 700 bar (just over 10,000 psi!) then it will be strong enough to hold together in an impact. My only concern is if the filling valve ruptures.......

6 June 2017
£61,500 purchase, nearly 5 metres long, 2 tonnes, range anxiety. But above all it get the 26 mpg, completely pointless. johnfaganwilliams :- last time I looked Hydrogen was just under £10.00 a kilo, oh, and it takes around 35Kw to produce 40 miles (1 kilo) worth OR enough to refuel a Leaf from empty! Another environmental reason why the EV has won the battle

6 June 2017
xxxx wrote:

£61,500 purchase, nearly 5 metres long, 2 tonnes, range anxiety. But above all it get the 26 mpg, completely pointless. johnfaganwilliams :- last time I looked Hydrogen was just under £10.00 a kilo, oh, and it takes around 35Kw to produce 40 miles (1 kilo) worth OR enough to refuel a Leaf from empty! Another environmental reason why the EV has won the battle

All of that is indisputable. But I think it an interesting proposition as a bridging stage from ICE to EV and obviously our cities would be a lot cleaner without diesels or even petrol engines around. Fossil fuel stations are abundant so plenty of scope to add Hydrogen infrastructure and fuel cell cars blow away the final hurdle to scrapping ICE cars, range anxiety. As people got used to driving motor propelled vehicles and realised they have come on a bit from Golf buggies many would find their needs could be covered by an EV instead (they would have continued to improve and get cheaper meanwhile) and start to transition into them on a larger scale. I am not convinced EV development will advance enough mid term for the masses to make a single leap. By that I don't just mean vehicle development as much as infrastructure development. Its probably easier to dig a hole and add a hydrogen refuelling tank than lay on several very high powered rapid chargers mid term. Long term we will have to upgrade the grid top to bottom, a vast project.

6 June 2017
I reckon the outcome for the Hindenberg would have been much the same if it had been full of petrol, but no one worries about driving round with a tank full of petrol. If you look up safety of hydrogen v petrol they have very similar risks overall, which are perfectly manageable.
Poor old xxxx "hydrogen cars just went pop" I suggest you may have jumped to the wrong conclusion....

6 June 2017
Well you're welcome to an opinion on my opinion but I didn't jump to the conclusion without thinking about it. If you think Hydrogen will outsell the EV then I respect that. p.s. I'm not that old either

6 June 2017
hmmm... Fair enough but its not entirely clean is it. The majority of usable hydrogen is collected as an over production at power plants when it becomes inefficient to turn down production (especially in coal burning). That then needs to be packaged and transported. I am no expert but with current production techniques, making a car takes quite a lot of energy too.

In complete contradiction of myself however, it takes this kind of development to influence market shifts so that future cars are as green as they can be.

6 June 2017
That same argument applies to the generation of electricity required to charge EVs. Once we get to the stage that renewable energy is plentiful enough to charge all the EVs manufacturers want us to buy, that capacity could be used to produce hydrogen for fuel cells instead.
The fact of the matter is there is no immediate solution to CO2 production, we therefore need to decide whether EVs or hydrogen (or something else) gives the best solution in the long term when we are fully reliant on electric power in one form or another. Personally I think, once fuel cells have had the amount of development that EVs have had over the last 20 years, they will win out, but who knows. I can't wait to see to be honest.


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