Honda FCX Clarity


The elegant form of the Honda FCX Clarity sets it apart from everything else on the road and complements the rational, environmental reasons for driving a fuel cell eletric vehicle. The sharp, dark chrome trim that runs from bumper to headlight draws the eyes toward the front wings, creating a powerful, dynamic look and a cool, clean, futuristic feel. The side mirrors add to the Honda FCX Clarity’s free-flowing cabin. Mounted on slender arms that blend with the door moulding, they emphasise the elegant lines of the side windows, with the moulding embracing the mirror housing. The exterior door handles have a spare, clean look that accentuates the slender lines of the body. Robust rear wings reinforce the compact cabin for a bold, sculpted look. The rear glass and contoured design of the rear combination lamps emphasise the vehicle’s wide, confident stance.


The most distinctive feature of the new one-motion design is found at the rear of the Honda FCX Clarity. To take advantage of the high-deck design and enhance rear visibility, the car is fitted with an extra window with visibility control-a feature carefully designed to protect privacy. The rear of the car is set high to ensure good luggage volume, and windows are positioned in the upper boot lid and in the barrier behind the rear seat to allow the driver to see into the boot.

Visibility control lets occupants see out without passersby seeing in

A special polycarbonate layer is applied to both sides of the window to make transparency dependent on the angle of vision, protecting occupants’ privacy. The result is excellent rearward visibility for the driver, with a high level of privacy for the rear-seat passengers.


Free-flowing, aerodynamic design capitalises on the new platform’s unique qualities

It is no coincidence that the exterior design’s key features-the front and rear wings, the front pillars, the tapered rear cabin-also contribute to outstanding aerodynamic performance. Superb aerodynamics are built into the free-flowing, one-motion form. And because there is no engine-and therefore no low-hanging exhaust system-the car’s underbody is flatter, reducing drag.

Lightweight aerodynamic wheels

Ultra-lightweight forged-aluminium 5-spoke wheels have fin-shaped plastic fairings to suppress air turbulence, reducing weight and improving aerodynamics while adding a sporty touch.

A unique new finish highlights the body’s complex surfaces and contours

The star garnet colour of the brilliant finish sets the Honda FCX Clarity’s one-motion body apart. The extraordinary depth and quality of the coating provides a deep, expressive lustre that changes character depending on the play of light and shadow across its surface. This is a premium vehicle inside and out.

A comfortable, spacious, futuristic environment


Personal spaces that submerge occupants in comfort


A floating, layered instrument panel for an advanced feel

Front pillars have been extended forward, while maintaining generous headroom proportions, to create a sense of space. The instrument panel is set off as a unified mass unconnected to the door line, making it appear to levitate. Bright colouring in the padding accentuates the airy, spacious feel.

An advanced cockpit for a futuristic experience

Naturally, because it’s a Honda, the FCX Clarity is fun and easy to drive. The new fuel cell multi-functional display in the cockpit, for example, features three-dimensional displays of hydrogen consumption, battery levels, motor output and other key information. The speedometer is positioned directly above the display to minimise eye movement. A compact electronic shifter that leverages the latest in drive-by-wire technology has been moulded into the dial visors. Other design touches enhance the futuristic feel, like the start switch beside the centre console that activates the fuel cell stack.

Fuel cell performance meters

The luminescent three-dimensional meters recessed into the instrument panel display all key driving information. A centrally located ball-shaped H2 meter keeps track of hydrogen consumption. The vehicle’s dials work together to provide an effective interface, providing the data output the driver needs.

The H2 ball-shaped hydrogen consumption gauge changes colour and size to reflect hydrogen consumption as driving conditions change. During high consumption, the ball becomes large and amber-coloured. As consumption decreases, it shrinks and turns yellow, then blue. The hydrogen fuel and battery gauges are to the right of the H2 ball-shaped meter. The fuel cell stack output gauge and battery output/charge display are on the outer perimeter.

Luxury from the future

Silver accents and blue acrylic in the inner door handle and audio panel impart a futuristic look. High-quality materials like wood-grain appearance panelling in the doors and luminous black lacquer headrests combine with warm colours for a luxurious, space-age feel.


To help move away from petroleum-based resins and other synthetic fibres toward plant-based fabrics, Honda created a new premium biofabric for vehicle interiors. Honda Bio-Fabric is a polyester material called poly (trimethylene terephthalate) (PTT), made by fermenting corn. Its texture and durability make it perfect for use in seat coverings, door linings, console trays and arm rests-any part of the vehicle where the occupants will appreciate its premium feel. Poly(lactic acid) (PLA) fibres made from corn and other plant biomass are used in roof linings, floor carpeting and boot linings. In fact, all interior fabric coverings in the Honda FCX Clarity are made of natural, plant-based materials.

Honda Bio-Fabric: outstanding elasticity and feel

The molecular structure of PTT fibre is finely kinked in an accordion-like structure, allowing it to stretch more readily than other fibres and return easily to its original shape, avoiding sagging. It also has a unique, silky feel not found in other coverings. That is why Honda Bio-Fabric is used on all surfaces that come into direct contact with the occupants.

The production process

The 1,3-propanediol, which forms the raw material for PTT fibres, is normally produced by chemosynthesis. In contrast, Honda Bio-Fabric is made from corn, using a bio-tech fermentation method. It is combined with terephthalic acid, a petroleum extract, to create PTT resin, which in turn is spun, made into fibres, dyed and turned into Honda Bio-Fabric.

Reducing CO2 emissions

Based on the product life-cycle from procurement of raw materials to production, Honda Bio-Fabric provides a CO2 reduction of 30% per Honda FCX Clarity automobile, compared to conventional polyester made from petroleum products.


Front-row independent temperature controls

To meet the expectations of premium automobile customers, the Honda FCX Clarity is equipped with dual zone climate control to ensure optimal occupant comfort and more efficient use of energy.

Climate-controlled seats

Temperature control devices built right into the seat cushions and seatbacks use fans to draw in air, which a thermo-electric device then cools (by absorbing heat) or warms. The air is then blown through the seats to maintain the desired temperature while maintaining the breathability of the urethane, permeable foam and upholstery layers. Since this process provides heating and cooling in direct contact with the occupants, it is faster and more efficient than air conditioning alone. Individual controls are conveniently located on either side of the centre panel, providing an advanced touch of comfort for the luxury customer.

Ample storage space

The Honda FCX Clarity is designed to meet every storage need. There are drink holders for each occupant and many other easy-to-use storage areas. A boot space, separate under-boot storage well and other innovations add up to storage volume comparable to other mid-size sedans.

Smaller. Higher output. The fuel cell electric vehicle has evolved

Honda fuel cell electric vehicles continue to lead the industry. Recognising that the fuel cell stack is the key to the fuel cell electric vehicle’s evolution, Honda has continued to improve performance and packaging. In 2003 Honda unveiled the Honda FC Stack, capable of sub-zero start-up and boasting outstanding production feasibility. Its design, featuring stamped metal separators and an aromatic electrolytic membrane, revolutionised the fuel cell. Next, Honda took up the challenge of structural innovation-creating the V Flow FC Stack with an original cell structure that delivers decreased weight, improved performance and even more compact design. The V Flow FC platform is the next generation in package design. It makes compelling styling and packaging feasible in a fuel cell electric vehicle for the first time. It is the breakthrough in stack technology that gives the Honda FCX Clarity its elegant design.

The new V Flow FC Stack: high output in a lightweight, compact design

The V Flow FC Stack features an entirely new cell structure that achieves a higher output of 100 kW, smaller size and lower weight, with a 50% improvement in output density by volume, and a 67% increase in output density by mass, compared to the 2006 Honda FCX Concept.

Layers of cells producing lots of energy

The Honda V Flow FC Stack uses a proton exchange membrane fuel cell (PEMFC) electrical generation system that directly converts chemical energy produced in hydrogen-oxygen reactions into electrical energy.

The extremely thin proton exchange membrane (electrolytic membrane) is sandwiched between pairs of electrode layers and diffusion layers (the hydrogen and oxygen electrodes) to form a membrane electrode assembly (MEA). The MEA is enclosed between two separators to form a cell-a single electrical generation unit. Several hundred cells are stacked together to form a fuel cell stack. As with batteries, these individual cells are connected in a series to produce a high voltage.

How electricity is generated

  • Hydrogen gas is passed over the hydrogen electrode. Each hydrogen atom is converted into a hydrogen ion in a catalytic reaction with the platinum in the electrode, releasing an electron.
  • Having given up its electron, the hydrogen ion passes through the electrolytic membrane, where it joins with oxygen from the oxygen electrode and an electron arriving via an external circuit.
  • The released electrons create a flow of direct current in the external circuit. The reaction at the oxygen electrode produces water as a by-product.
  • Because the electrolytic membrane must be kept continually damp, it is necessary to humidify the supply of hydrogen and oxygen. The water by-product is recycled for this purpose. Unneeded water and air are released as exhaust.

Electrical power on demand

The main components of the fuel cell electric vehicle’s powerplant are the fuel cell stack, which generates electricity from hydrogen, the hydrogen tank, the lithium ion battery, the electric drive motor and the Power Drive Unit (PDU), which governs the flow of electricity. Because the vehicle is propelled by an electric motor, it delivers smooth, powerful acceleration and quiet operation, without the noise and vibration associated with an internal combustion engine. During start-up and acceleration-when a large amount of power is required-the electricity from the fuel cell stack to the drive motor is supplemented with electricity from the lithium ion battery to provide powerful performance. During deceleration, the drive motor works as a generator, converting kinetic energy into electricity, which is stored in the lithium ion battery along with any excess electricity produced by the fuel cells. When the vehicle is stationary, an idle stop system shuts down electrical generation in the fuel cell stack. Electricity from the lithium ion battery ensures continued operation of the air conditioner and other devices. The system optimally controls electrical power, resulting in highly efficient operation.

Another key advance: a vertical gas flow cell structure is combined with wave flow-channel separators for an even more compact, lightweight design

Until now, hydrogen and air flowed horizontally through the cells of Honda fuel cell stacks. The new V Flow FC Stack introduces a cell structure in which hydrogen and air flow vertically, and gravity is used to facilitate more efficient drainage of the water by-product from the electricity generating layer. The result is greater stability in power generation. The new structure also allows for a thinner flow channel and reduction in the stack’s size and weight. And Honda’s innovative and original wave flow-channel separators provide a more even and efficient supply of hydrogen, air and coolant to the electricity generating layer. The results are higher generating performance, optimal cooling characteristics and major reductions in size and weight. More compact, the new stack has far fewer parts and can fit into a single box. It is also much easier to manufacture.

V Flow cell structure for greater stability in electrical generation and a thinner design

In addition to allowing hydrogen and air to flow vertically, the V Flow design also means that water drainage is assisted by gravity. Water does not collect on the electrical generation layer, ensuring constant power generation. This also allows flow channel depth to be reduced by 17%-a major contributing factor in creating thinner cells and a more compact stack.

Wave flow-channel separators enable a smaller stack design

The fuel cell consists of a membrane electrode assembly (MEA)-an electrolytic membrane sandwiched between the pairs of electrode layers and diffusion layers forming the hydrogen and oxygen electrodes-which are in turn enclosed between separators containing flow channels for hydrogen, air and coolant. The V Flow FC Stack incorporates wave-shaped vertical flow channels for the hydrogen and air, with horizontal coolant flow channels weaving between them. The wave flow channels provide greater flow length per channel than straight channels, while the resulting turbulent flow within the channel promotes improved hydrogen and air distribution. As a result, the hydrogen and air are spread over the entire electrode layer, making more efficient use of the compact electricity generation layer and achieving approximately 10% higher generating performance than with straight flow channels. The horizontal coolant flow also ensures more even cooling over the entire electricity generation layer, allowing for a reduction in the number of cooling layers to half that of previous stacks. The previous stack had one cooling layer for each cell. The new stack needs only one cooling layer per two cells. This results in a 20% reduction in stack length and a 30% weight reduction-a major breakthrough in compact, lightweight stack design.

Improved heat mass allows start-up at -30˚C

Improved water drainage due to the V Flow cell structure facilitates better output immediately after start-up. The reduced coolant volume and single-box design made possible by the wave flow-channel separators results in heat mass 40% lower than previous stacks. As a result, the amount of time required to achieve 50% output after start-up at -20˚C is only one-quarter that of the previous stack. Start-up is now possible at temperatures as low as -30˚C.

Distributing the powerplant redefines the basic configuration of the automobile

The most distinctive feature of the fuel cell electric vehicle-other than the fuel cell itself-is the layout flexibility made possible by the fact that the powerplant and drive train can be distributed throughout the vehicle. In order to take full advantage of this feature, each component in the powerplant must be made extremely compact. To this end, each part of the fuel cell stack-the drive motor and gearbox, the power drive unit, the lithium ion battery and even the hydrogen tank and radiators-have been made as compact and as efficient as possible. This creates maximum freedom to optimise the position of each part to achieve the spacious, full-cabin design unique to this new fuel cell electric vehicle. The end product is the embodiment of Honda’s man maximum, machine minimum design philosophy-and the next generation in human-friendly automobiles.

The V Flow FC Stack is located inside the centre tunnel, and the lithium ion battery is placed under the rear seat. The result is a free-flowing, full-cabin design with a long wheelbase that provides the spacious and comfortable seating that customers expect in a luxury car.


Vertical gas flow, with the cells of the fuel cell stack configured so that hydrogen and air flow from top to bottom

Vertebral layout, with the fuel cell box oriented longitudinally along the centre tunnel

Volume-efficient package and low-floor platform

The technology – a powerplant that is sure to spark a revolution in design, packaging and performance

In addition to making the fuel cell stack, drive motor and other individual components more compact, parts have been consolidated into modular units. The result is an amazingly compact and lightweight design-180 kg lighter and 45% smaller than the previous powerplant.

A significantly more compact, unified fuel cell system

The fuel cell stack is now contained in one box instead of two. This reduces the number of parts required to connect the stacks together and allows the hydrogen supply system, humidifier system and contactors to be combined into a single unit that is 65% smaller than the previous system. This makes it possible to locate the stack in the vehicle’s centre tunnel rather than under the floor, achieving a low-floor, low-height body design.

Compact, high-efficiency lithium ion battery requires less space


Three radiators integrated into one

Increased powerplant efficiency, vehicle weight reduction and improved aerodynamics have resulted in a major reduction in heat generation. The cooling air vent for the motor bay has been reconfigured and the cooling capacity of the radiators increased. These improvements made it possible to integrate the fuel cell radiator, the drive train radiator and the air conditioning condenser into a single three-layer unit. The new radiator unit requires 40% less space, contributing to the stylish short-nose design.

Unified coaxial drive motor/gearbox and PDU


This coaxial motor/gearbox is further combined with the Power Drive Unit (PDU) in a unified configuration that saves another 240 mm in height. These innovations make possible the Honda FCX Clarity’s stylish, short-nose design.

Integration of functions in hydrogen tank

This creates more space for the rear seats and boot. The shut-off valve, regulator, pressure sensor and other components in the refuelling and supply system were integrated into a single in-tank module, reducing the number of parts by 74%. Tank capacity is greater, installation space efficiency is 24% better, and vehicle range is increased.

A distinctive driving experience created by the high-output electric motor

Along with uncompromising performance, the electric motor- driven Honda FCX Clarity delivers a completely different driving sensation from a conventional vehicle powered by an internal combustion engine. There are no gear changes to interrupt power delivery and the torque characteristics are smooth, making acceleration seamless and robust. This is a key part of its distinctive, premium driving feel. There is none of the vibration that comes from reciprocating pistons. There is no combustion noise-just quiet, clean, vibration free performance.

Start-up and acceleration times are comparable to that of a 2.4-litre internal combustion engine vehicle of similar size.

The Honda FCX Clarity’s high-efficiency powerplant and outstanding energy management result in an exceedingly high operating energy efficiency. Furthermore, vehicle weight reduction and superb aerodynamics contribute to an approximate 20% improvement in fuel economy. Hydrogen tank capacity has also been increased, extending vehicle range by 40%.

Higher output, high torque, higher rpms. Quieter operation in a more compact design

The new drive motor configuration was developed to deliver more powerful acceleration and a higher top speed, along with a quieter, more luxurious ride. The new rotor and stator feature a combined reluctance torque, low-loss magnetic circuit and full-range, full-digital vector control to achieve high efficiency and high output over a wide speed range.

The innovative shape and layout of the magnets in the rotor result in high-output, high-torque, high-rpm performance. These innovations deliver a maximum output of 100 kW along with impressive torque and power output density. At the same time, resonance points in the high-frequency range have been eliminated for quieter operation.

New rotor delivers high-output, high-torque, high-rpm performance

A newly designed rotor features an Interior Permanent Magnet (IPM) to lower inductance, improving reluctance torque for high-torque performance. The magnet’s high-energy characteristics also contribute to high torque and a more compact design. These innovations result in 50% higher output density and 20% higher torque density. The number of poles has also been reduced and the magnet widened to better withstand stress, allowing the yoke to wrap around the outside of the IPM. A centre rib has been installed for greater rigidity. This more robust construction allows for operation at higher rpm.

New stator contributes to high torque and efficiency

The stator features a low iron-loss electrical steel sheet and higher density windings that decrease resistance and contribute to high torque and higher output.

Number of poles reduced to eliminate resonance points and produce quieter operation

The number of magnetic poles in the rotor has been reduced from 12 to 8, eliminating resonance points within the operating rpm range. The result is outstanding quietness and higher output.

Coaxial gearbox conveys motor output directly for a major improvement in compact design

The motor’s rotor shaft features a hollow construction, with the driveshaft passing through its centre in a coaxial configuration. This arrangement, unique to electric vehicles, allows the motor and gearbox to be combined into a single, compact unit, while providing highly efficient transmission of the motor’s high-output, high-rpm power to the driveshaft. Innovative bearing design and fewer rotor oil seals result in lower friction for higher transmission efficiency, creating driving performance with a more direct feel.

Shift-By-Wire for simpler and easier operation

The vehicle’s fixed gear ratio allows for simple operation: there’s an easy-to-use shift control for forward, reverse and park that has a light touch and a short stroke. The compact shift unit features electronic control, allowing the shift lever to be installed on the dashboard. The shifter, start switch and parking switch are all easy to operate. Other operating systems are also laid out in separate zones to improve ergonomics.

Power assist and efficient regeneration with an advanced lithium ion battery

The compact, high-output lithium ion battery assists the fuel cell in powering the vehicle. The advanced battery provides a powerful supplement to the fuel cell stack’s output, powering the motor for torquey off-the-line acceleration. In addition to increasing the total energy capacity, the battery efficiently stores energy generated by the intelligent regenerative braking system, capturing 11% more kinetic energy than the ultra-capacitor used in the 2005 FCX. Some 57% of the energy of deceleration is regenerated with the new system.

As a result of increased energy storage capacity and a broader range of regeneration control, it has been possible to implement a system that regulates acceleration and reduces the need for pedal operation in downhill driving. Assessing incline and vehicle speed, the system regulates acceleration when the driver first releases the accelerator pedal, minimising the need for frequent braking. The system simultaneously adjusts the amount of regenerative braking to help maintain constant vehicle speed after brake pedal inputs. The function is similar to engine braking in a conventionally powered vehicle, but more intelligent, smoother and easier to use.

Superior chassis dynamics for greater comfort, safety and driving pleasure

Optimal geometry front and back, including carefully calibrated toe response to the suspension stroke and camber angle, maximise tyre contact with the road during cornering for highly responsive, stable handling. Optimisation of the anti-dive angle and control of vehicle behaviour during deceleration contribute to an even, comfortable ride.

The lowered front suspension adds to the visual impact of the short-nose design. In addition to the implementation of a 5-link double-wishbone rear suspension, forged aluminium lower arms, high-capacity trailing arm bushings and reduced unsprung weight smooth out bumps in the road.

Responsive electric power steering for a 5.4m turning radius and tight cornering

Along with a newly implemented brushless motor with increased output, the front double-wishbone suspension helps facilitate tight cornering and delivers a 5.4m turning radius-a very tight turning radius given the vehicle’s long wheelbase. The low inertia of the motor and minimal friction of the suspension when turning contribute to smoother steering. And a tilt-and-telescopic steering wheel provides an optimal steering position for a wide range of drivers.

Vehicle Stability Assist (VSA) integrated with electric power steering (EPS) for enhanced handling

The Honda FCX Clarity features an integrated braking, traction control and electric-controlled steering system that works in concert to help the driver maintain control of the vehicle in emergency manoeuvres and in varying road conditions. Working in conjunction with the vehicle’s anti-lock brakes, Traction Control System (TCS) with slideslip control and Vehicle Stability Assist (VSA), the Electric Power Steering (EPS) enhances steering force for even better handling.

  • In controlling understeer, EPS provides supplementary steering force to prevent the steering wheel from being turned too far as motor torque is reduced and braking force is applied to the inner rear wheel by the VSA.
  • In controlling oversteer, the EPS provides steering force to help the driver counter the spin-generating moment as braking is applied to the outer front wheel to stabilise the vehicle.
  • When road conditions under the left and right tyres are different, torque and steering force are supplemented to help the driver maintain stability.

Complementing the linear torque control of the drive motor, TCS provides enhanced grip and control in acceleration

Increased motor torque responsiveness during TCS operation has made a major contribution to suppressing excessive tyre slip. Improvements to the total system deliver even more precise torque transmission and improved grip for confident acceleration even on slippery surfaces, and improved control in acceleration.

Striving to protect vehicle occupants

To enhance occupant protection in a collision, Honda has implemented innovative body technology with a network of frame structures in the front of the vehicle along with additional safety precautions appropriate to a fuel cell electric vehicle. The vehicle is designed to comply with all applicable federal motor vehicle safety standards.



Taking full advantage of the distributed powerplant layout, we have optimised the body structure. To help protect occupants in the event of frontal collisions, the straight front-side frame, upper frame and lower structural parts are designed to disperse and absorb impact energy. Energy is dispersed through the front pillars and floor. The lower structural members are designed to help prevent misalignment with the impact-absorbing parts of the other vehicle. Along with an energy-absorbing upper frame, they efficiently disperse energy over a wider area. This design is intended to both reduce the impact forces on Honda FCX Clarity occupants as well as on the other vehicle. The enhanced rigidity of the body also increases overall vehicle refinement.

The impact-absorbing front-end design helps enhance pedestrian protection

To help protect pedestrians, we have designed the Honda FCX Clarity’s fenders, bonnet hinges, wiper pivots and other components to more efficiently absorb collision impact.

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