First drive: Honda FCX Clarity Hydrogen Car

Hydrogen fuel cell vehicles are decades away from being mass-production reality, but we can already tell you what one is like to drive.

The car of the future still starts with a key

There's just a muted whirring, though, as you twist the key to the "on" position and press the "start" button, primary colours illuminating the instrument panel ahead and the display stating simply: “Ready to drive.” There's more convention to flicking the small dash-mounted transmission lever to D, depressing the foot-operated parking brake and applying pressure to the throttle pedal, but from there driving the Honda FCX Clarity hydrogen fuel cell vehicle is an experience of the slightly abnormal variety.

A glowing green battery meter on the left of the display indicates the Clarity is initially being powered by the car's lithium-ion battery, before transferring to the main source of the car's propulsion shown as a blue meter — hydrogen fuel.

Bars illuminate incrementally on the "power meter", which is divided into 10 segments of 10kW, revealing the Clarity's total output of 100kW. There's also 256Nm of torque, developed between 0-3000rpm.

In the middle of the digital dial, a coloured ball expands and changes from green to amber whenever a leaden right foot prompts heavier consumption.

The Clarity is essentially an electric car, though unlike EVs that need several hours to charge, the Honda generates its own power supply through a fuel-cell stack that converts the hydrogen fuel and oxygen stored in a tank under the boot into the electricity needed by the drive motor to power the front wheels. The fuel cell is supplemented by a lithium-ion battery that is recharged during deceleration and braking, similar to a hybrid.

Acceleration is accompanied by an eerie hush, the silence broken only by an ascending whine from the electric motor, a hydraulic-like sound from the air compressor (which feeds atmospheric oxygen to the hydrogen tank) and tyre and wind noise, which is only minor.

The Clarity doesn't feel especially quick — 0-100km/h is completed in about 10 seconds with a top speed of 160km/h — but throttle response is rewardingly immediate and the vehicle's momentum builds in a linear fashion courtesy of a single-gear transmission.

The drivetrain's smoothness is just one element of the Clarity's impressive breadth of refinement.

The ride proved to be mostly supple on California's inconsistently surfaced road network, though this doesn't translate into poor body control when the Clarity is tackling a mountain road.

The regenerative brakes take some adjustment, though, because there is surprising immediacy to their bite.

The Clarity sits on an exclusive platform and almost looks like a conventional five-door hatchback, albeit with a slightly futuristic swoopy, elongated silhouette, as well as an unusual tapered and ducktailed rear end.

Honda says the Clarity would be priced like a luxury car even when it becomes commercially available in about nine years' time and the cabin quality and specification is meant to sit between a high-end Honda (such as the Accord) and an Acura (a highbrow badge the company uses in the US).

There's a stylish mix of soft and hard plastics throughout the Clarity, while the interior design looks mostly familiar with the exception of a space-age binnacle display.

The seats — made from eco fabrics — are comfortable and there's generous room for the driver and front passenger and two occupants in the rear, as well as plenty of storage.

Only boot space is affected by the Clarity's futuristic componentry, with the hydrogen tank significantly eating into luggage room. A concealed storage compartment under the boot floor helps, though there's no room for a spare tyre (there's a tyre inflator and sealant instead).

Refilling the Clarity couldn't be simpler and would be familiar to owners of LPG cars. You open the fuel flap, attach the hydrogen pump nozzle and lock it into position, then press a button to start filling the vehicle with up to 4.1 kilograms of compressed (5000psi) hydrogen gas.

It takes minutes and you're good for more than 400 kilometres.

Hydrogen costs $US5 ($A5.40) a kilogram in California, the equivalent of half the cost of a gallon (3.8 litres) of "gas" in North America, for double the efficiency. The hard part, for some years yet, will be finding a hydrogen station.