Everything, but not as much as you'd think. The Mirai is one of the first production hydrogen vehicles, so it's part of a huge watershed moment, but ultimately it's a normal car with fuel contained in tanks and an electric hybrid system that sends power to the front wheels. A lot like a Prius, only running on something a lot cleaner.
The dashboard and centre console are futuristic enough without being scary, and there are familiar touches like Toyota's nifty little automatic gear lever sticking up near the steering wheel. You'll find a whole range of drivetrain-related displays that can tell you what's going on underneath you, which is cool. Again, a lot like the Prius.
Looks and image
Aerodynamics are paramount for the Mirai, hence the unusual styling that enhances both the cooling systems and the drag coefficient; how smoothly the car cuts through the air. The underneath is completely flat, for starters, which can only be done because there are no hot gases around the engine bay.
It would take a brave person to call it pretty, but the functionality within its lines holds the right kind of appeal for early adopters and the eco-minded, both of whom will want to be seen to be driving such a revolutionary concept. Driving a car but emitting nothing but water vapour is something to be proud of.
Space and practicality
There's a 361-litre saloon boot, which is good enough for most needs. You can forget that trip to the oak furniture place, but everyday luggage will be fine. There's loads of rear legroom for average-height adults and despite the Mirai's slender, gap-threading footprint on the road it feels wide inside thanks to liberally-applied horizontal lines across the dashboard.
While a 300-mile real-world range is easy, the obvious limiting factor here is the current availability of hydrogen filling stations. There, err, aren't many. Yet. Watch this space.
Behind the wheel
Supreme quietness is what greets you inside the Mirai. The chief engineer describes difficulties in controlling road noise in such a silent car, but he's being modest. Squeeze the throttle hard and you'll hear the fake whirring noise added to let owners feel a more natural sensation of acceleration and likewise in reverse when you lift off the right-hand pedal.
Fantastically usable torque from the hydrogen-electric drivetrain makes the Toyota a dream to drive around town and the suburbs. It gets up to speed with less fuss than a dinner at Downton. The ride is impeccable, too; settled and comfortable. It makes you wonder why all cars aren't like this. Three driving modes allow you to bias the system towards the electric motor, a calculated mix of that and the hydrogen, or towards maximum output.
Outward visibility is great, giving clear views of approaching traffic at roundabouts. Everything within touching distance feels high-quality, too, including the very comfortable eight-way electrically adjustable front seats.
Value for money
Here's the rub: the Mirai costs £66,000 on the road, or £750 per month on an all-inclusive leasing deal that covers servicing, tyres and the like. You get an awful lot of day-brighteners for that, like heated seats (all round), heated steering wheel and even heated windscreen wipers. There's no denying that this will be a deeply lovely car to own or lease, but it's a bit rich for most people.
Who would buy one?
Toyota is targeting the Mirai partly at wealthy early-adopters who live near refuelling stations. But greater uptake is expected among companies looking to reduce their carbon footprint and to be seen doing it. Transport for London is already a customer, and large carbon-sensitive corporations could well join in with a couple of cars for the right executives.
This car summed up in a single word: Serene
If this car was an : alien race it would come in peace, bringing chocolate biscuits and hugs for all.
FACTS AT A GLANCE
Toyota Mirai, from £66,000
Engine: 2.0-litre turbocharged petrol producing 152bhp and 247lb/ft
Transmission: Single-speed automatic driving the front wheels
Performance: Top speed 111mph, 0-62mph in 9.6 seconds
Economy: 1.23kg per 100 miles combined
Emissions: Water vapour