Well, the revolutionary technology, which is essentially a hybrid drive system that instead of using electric motors to support an internal combustion engine, uses compressed air, will be appearing at the 2013 Geneva Motor Show next month.
It will feature in a Citroen C3 subcompact, which its makers claim is capable of returning a fuel economy of 78 mpg on the European combined cycle thanks to the technology.
In addition to being much more fuel efficient than comparable gas-electric hybrids, and even some more advanced plug-in hybrids, the Citroen C3 Hybrid Air concept is said to be lighter and much cheaper to produce as there are no heavy and expensive batteries. It also operates at a constant level of efficiency, regardless of weather or driving conditions.
The technology was developed by PSA Peugeot Citroen in cooperation with automotive supplier Bosch and draws from the Citroen brand’s historic expertise of hydraulic systems for cars.
Citroen, of course, used pressurized air and hydraulic systems to manage the suspension, steering, braking and semi-automatic gearbox of the legendary DS as far back as 1955. The automaker also showcased one of its original 2CVs fitted with a hybrid setup that combined a gasoline engine and similar pressurized air and hydraulic system in 1958.
Given the concerns about fuel costs and the environment, the French automaker is now investigating the use of the technology once again.
The latest setup combines a gasoline engine with a compressed air storage unit, a hydraulic motor and an automatic transmission with an epicyclic design. An intelligent electronic management system manages input from the driver to optimize energy efficiency with three operating modes: Air Mode, Gasoline Mode, and Combined Mode. Optimizing energy efficiency in this way cuts fuel consumption and allows the system to recharge the energy storage unit with compressed air, using regenerative forces to suck in air and compress it for later use.
Air Mode is used for driving around town, at speeds of up to 43 mph. Here, the gasoline engine is not used. The compressed air is transmitted to the wheels via the hydraulic motor and gearbox. Depending on traffic, this mode will be active between 60 and 80 percent of urban driving time. Maximum use of deceleration and braking energy will ensure efficient recharging of the compressed air unit.
Gasoline Mode is used mostly on the highway of if there is no more compressed air. Again, the energy from deceleration and braking is recovered for use when in Air Mode or for the boost function in Combined Mode.
Finally, in Combined Mode, the gasoline engine and hydraulic motor work together. This mode is used particularly during initial start and strong acceleration.
If further tests prove successful, PSA Peugeot Citroen hopes to have the first production applications ready by as early as 2016. Note, its makers claim the technology is only suitable for cars in the subcompact and compact segments.