Citroen Launches The Green Rally Car

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CITROEN LAUNCHES THE GREEN RALLY CAR

Citroen brought together its remarkable record in the World Rally Championship and its unique environmental technology to produce the world’s first hybrid World Rally Car, the Citroen C4 WRC HYmotion4 with a hybrid energy recovery system which delivers added performance and lower emissions.

Unveiled this week (2 October 2008) at the Paris Motor Show, this new concept car – which sports a split livery, with the team's familiar World Rally Championship colours on one side, and a design based on a more restful colour scheme redolent of natural materials on the other – illustrates Citroën's stand on environmental matters, including in the world of motor sport which stands out as a source of performance-related, reliable and rational technological innovations.

The HYmotion4 system enables a proportion of the kinetic energy produced during braking to be recovered and stored. This energy is accumulated by a motor-generator in the form of electricity in battery packs positioned at the rear of the car. It can then be employed either to deliver extra power when accelerating or to drive the car using emission-free electrical power alone, with no engine noise or exhaust fumes between rally stages.

This system can significantly enhance the efficiency of a competition car during the different running phases:

• Braking energy is not entirely dissipated in the environment as waste heat.

• The availability of additional torque thanks to an electric motor increases the internal combustion engine's useful rev range.

• At a constant speed in electric mode, the vehicle benefits from a longer range (more than an additonal 40km), while fuel consumption on road sections is reduced by 30 per cent.

These real performance gains have been achieved thanks to the innovative technological solutions which have been developed to transform the C4 WRC into the C4 WRC HYmotion4. The system comprises four key components:

• A 125kW electric motor-generator connected to the rear differential (gear driven),
• A pack of 990-cell lithium-ion batteries which deliver a voltage of 400V. Positioned over the fuel tank.
• Two additional cooling systems for the motor-generator and batteries, with a specific radiator positioned under the right-hand side of the floor.
• An electronic control unit to manage the system's power electronics circuit.

The driver is free to select one of the four running modes using the HYmotion4 pre-selection rotary control:

• Internal combustion engine mode: the most frequently-used mode for the C4 WRC (used on stages and some on road sections).

• Internal combustion engine mode with energy recovery: activated on stages; improves the brakes' resistance to fade and charges the batteries.

• Electric motor mode with energy recovery: used on road sections (untimed), in built-up areas or in the service park; contributes to increasing the car's range, reduces noise in built-up areas, and permits the internal combustion engine not to be used when it is not indispensable.

• Boost mode (internal combustion engine and electric modes combined): can be selected at the desired moment on a stage to benefit from an additional 300Nm of torque for a limited time.

This performance gain makes optimising energy management a new parameter for rally drivers to master.

C4 WRC HYmotion4 fits perfectly with Citroën's long-term commitment to motor sport and its consequential environmental policy. This concept underpins the brand's policy to conceive very high performance cars which respect the environment and is the first step prior to other developments which will be guided by future evolutions to the FIA regulations.

ENDS

Engine
Turbocharged
Developed from the EW10J4S engine
Position: transversely mounted, angled 25° towards the exhaust side
Number of cylinders: 4 (in line)
Block: aluminium
Cubic capacity: 1,998cc
Maximum power: 320bhp at 5,500rpm
Maximum torque: 58mkg at 2,750rpm

Hybridization
Motor-generator: 125kW and torque of 300Nm-1 (rear differential).
Lithium-ion battery: 990 cells, 400 Volts, 22Ah (positioned over fuel tank).
Electronic management: CITROEN SPORT
Modes: internal combustion engine mode, electric motor mode, boost mode (internal combustion engine + electric motor modes)

Ignition
ECU: Magneti-Marelli MHT460
Flex Ray drive-by-wire

Timing
Belt-driven double overhead camshafts
Four valves per cylinder

Transmission
Four-wheel drive
Triple-plate carbon clutch
Mechanical front and rear differentials
Active centre differential
Six-speed semi-automatic sequential gearbox

Front brakes
Asphalt: ventilated discs, six-pot callipers
Gravel: ventilated discs, four-pot callipers

Rear brakes
Asphalt and gravel: ventilated discs,
four-pot callipers
Adjustable front/rear bias
Hydraulic handbrake

Suspension
Front and rear: MacPherson-type with coil springs
Dampers: Citroën/Exe-TC

Steering
Hydraulic power assisted

Wheels
Asphalt: 8 x 18 inch
Gravel: 7 x 15 inch
Asphalt tyres: Pirelli P0
Gravel tyres: Scorpion

Dimensions
Length: 4,274 mm
Width: 1,800 mm
Wheelbase: 2,608 mm
Front and rear track: 1,598 mm

Weight
1,350kg

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