PSA unveils gasoline-compressed air hybrid drivetrain

The innovative system can cut fuel consumption by up to 45 percent in city driving.

PSA Peugeot-Citroën has announced that it is in the early stages of developing a hybrid drivetrain that utilizes both gasoline and compressed air to generate energy. Appropriately called Hybrid Air, the system is being developed jointly with Bosch.

The French automaker bills the Hybrid Air system as a less complex, lighter and less expensive alternative to traditional gasoline-electric hybrids. It uses a hydraulic pump mounted on top of the gearbox to turn the kinetic energy that is generated while braking and decelerating into compressed air that is then transferred to a tank-like accumulator mounted under the trunk floor. This eliminates the need for a bulky battery pack.

The Hybrid Air system offers three driving modes: Gasoline, hybrid and air. Used mostly at freeway speeds, the first mode shuts down the compressed air system and the car relies solely on a three-cylinder gasoline engine with a displacement that hovers around 1.0-liter.

In the hybrid mode, the compressed air stored in the accumulator is converted back into energy and transferred to a hydraulic motor installed in the gearbox. The energy is sent to the front wheels, giving the car a boost under heavy acceleration or when going up a steep hill.

When the car is traveling in air mode, the internal combustion engine is turned off and the aforementioned hydraulic pump spins the front wheels by itself by converting the compressed air into energy. Primarily designed for city driving, the air-only mode can cut fuel consumption by up to 45 percent.

The system adds about 220 pounds to the weight of a sub-compact hatchback such as the Peugeot 208 or the Citroën C3. It is designed to work with an semi-automatic gearbox but Peugeot has declined to provide precise details about it.

PSA's Hybrid Air is still at the embryonic stage of development and it is not expected to make its production debut until 2016 at the earliest.

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