Battle of zero-emissions cars: Hydrogen or electric?
When Toyota puts its considerable bulk behind a new technology, everyone should sit up and take notice.
When it launched the first-generation Prius back in 1997, many scoffed. It was ugly, not terribly efficient and distinctly uncool. Eighteen years later, Toyota has sold nearly five million of the Prius, and it is now the best selling car in Japan.
And so enter the Toyota Mirai, leading the charge for hydrogen vehicles, alongside Hyundai's ix35 model.
The, now rather tired, joke about hydrogen is that it is "the fuel of the future, and always will be".
Fuel cells were invented in the 1880s and work by taking hydrogen fuel and reacting it with oxygen to produce electricity. The only waste product is water.
The problem with fuel cells has always been their cost, usually measured in millions of dollars.
Somehow, with the Mirai, which is the Japanese word for future, Toyota has managed to bring the price down to around $60,000 (£38,884) and to squeeze it all into a family-sized car.
'Big, heavy, expensive'
The first thing you notice getting into the Mirai is its size. It is nearly 5m (16 ft) long.
When trying to manoeuvre it out of the underground parking garage at Toyota's Tokyo headquarters I was convinced I would scrape the long nose against the concrete wall.
It also feels heavy, because it is: nearly two tonnes.
And then there is that price. It maybe cheap for the amazing technology packed in to it, but you can get a top of the range BMW 5 series or Mercedes E Class for less.
It is big, heavy and expensive. So why is Toyota building this rather than, say, a conventional battery powered electric vehicle? The short answer is range.
From Toyota's headquarters, I cruised silently down to Japan's first hydrogen filling station near to the Tokyo Tower. A full refill took just three minutes.
Once back behind the wheel the Mirai's computer told me I could drive 350 km (220 miles) before needing to fill up again. That is more than twice the range of most battery electric vehicles currently on the market (although Tesla's Model S goes further).
Bigger vehicles can have bigger hydrogen tanks and so longer range still. This is especially true for hydrogen fuelled trucks and long distance buses.
Toyota clearly believes the age of zero emissions vehicles is here, and that hydrogen technology is going to be a big part of it.
Nissan's electric bet
That is a big contrast to Toyota's old rival down the road in Yokohama - Nissan.
The boss of Nissan, Carlos Ghosn, has not been shy about expressing his disdain for hydrogen. Instead, Nissan is betting on lithium-ion batteries.
Mr Ghosn also scoffs at the whole issue of "range anxiety" in battery electric vehicles.
Speaking to him at the Tokyo motor show at the end of 2013 he gave me this response: "Where is all the hydrogen infrastructure?" he asked. "It doesn't exist, it still has to be built. Where is the electricity infrastructure? Everywhere!"
This is a fair point. Right now, the infrastructure to support hydrogen vehicles is still patchy.
To recharge your electric car, on the other hand, all you need is a power socket. The downside is that most battery electrical vehicles now on the market not only have limited range, they take a long time to recharge: up to eight hours.
But that is changing.
To find out how, I thought it only fair to take a look at Nissan's alternative to the Mirai - the Leaf.
The Leaf is not new; it's already been on sale for four years. It has come in for its fair share of criticism; that its real world range is much shorter than Nissan's claims and that its battery life deteriorates faster.
Once behind the wheel, the Leaf is immediately impressive.
It feels and drives just like a normal family hatchback, except it is completely silent, and has rather astonishing acceleration. You very quickly learn that using that acceleration kills its range.
Driving a battery car requires delicacy. You must stroke the accelerator rather than jamming it to the floor. But even with the gentlest of right feet, you will struggle to get more than 150km from one charge.
This is where technology again steps in.
Nissan's satellite navigation software tells you where all the charging stations are. Alternatively, you can press a button on the dash and the car will call a Nissan operator who can track your Leaf via GPS and tell you how to get to the nearest "quick-charge" station.
"Quick charge" must be the future for battery-powered cars, and the key to ending range anxiety.
Unlike your home electricity supply (which runs on 110 or 240 volts AC), quick charging stations supply 500 volts DC at a much higher current of 125 amps. Because of that, it can recharge your battery much faster.
Using one just outside Yokohama we managed to refill the Leaf's battery to 80% in just 25 minutes.
Hydrogen vs electric
Right now, Toyota and Hyundai are both betting on hydrogen power. Honda says it will soon follow.
But these new models are not about to change the world overnight. Just 700 of the Mirai will be made this year. If you order one now, the soonest it will arrive on your driveway is 2018.
If you want a battery car, on the other hand, there is much more choice and it is cheaper.
You can get the Leaf for around $26,000 (£17,000).
Last year, BMW launched the impressive i3. Renault's Zoe model already offers a more affordable option. Ford, Volkswagen, Kia and Mercedes are all following with their own battery electric vehicles.
And then there is the Tesla S, the most expensive and luxurious battery car yet. The Tesla also has a range of more than 400km (250 miles) on one charge.
The really exciting thing about all of this, battery electric or hydrogen fuel cell, is that, after decades of false starts, the era of zero emissions vehicles has finally arrived - and, in the opinion of this test driver, they seem pretty good.