Clever. The air hybrid powertrain that Citroen will be bringing to the Geneva Motor Show next month is nicknamed N-Air-Gy. Or, at least, that's what it says in the rendering that Citroen released today in preparation for the Swiss event. We've heard about this technology before, with the hint that it might some day go into one of PSA Citroen's B-segment compact hatchbacks. In Geneva, the powertrain will be displayed in a C3 VTi 82 hatchback.

Officially called Hybrid Air, this powertrain, co-developed with Bosch, pairs a gasoline engine with compressed air hybraulic power. In other words, Hybrid Air takes the battery out of the traditional hybrid set-up while gaining similar fuel economy benefits. In the C3 concept, that means "record-breaking" fuel economy of just 2.9 liters per 100 km (roughly 81 miles per gallon, on the lenient European test cycle). Citroen says this is 45 percent less, in urban settings, than a similar ICE vehicle because the car moves using a hydraulic compressed air system that is "recharged" using regenerative brakes. An air hybrid car should also be cheaper than a similar vehice with a standard hybrid powertrain. Citroen says an air hybrid system doesn't impact on cargo space, making it all the more appealing in smaller vehicles. We'll learn more in Geneva.
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After pioneering the particulate filter and Stop&Start, leading the way in diesel hybrid technology with the Hybrid 4, and being the first to market an electric car, CITROËN is continuing the offensive at the Geneva Motor Show with another high-tech breakthrough: the Hybrid Air system.

A full-hybrid solution combining compressed air and hydraulic power, Hybrid Air draws upon expertise that is written into the Marque's DNA.

It is an innovation that reflects CITROËN's consistent aim of developing technologies available to everybody and for all types of use.

Hybrid Air delivers breakthrough performance with fuel consumption of less than 3 litres/100 km and no additional battery, for:

- an even smaller environmental footprint,
- a more affordable price
- and no impact on onboard space.

This revolutionary technology is particularly well suited to models in the B and C segments as well as LCVs. On the Marque's stand at the Geneva Motor Show, it can be seen on a CITROËN C3 prototype that boasts record-breaking fuel consumption of 2.9 l/100 km (69 g of CO2/km). It also cuts fuel consumption and CO2 emissions by 45% in urban driving, compared with an ICE vehicle fitted with the same engine.

Karim Mokaddem, Hybrid Air project manager, will be present during the press days. He will respond to requests for interviews and explain how Hybrid Air technology works, with details on operation and performance figures. Several events will be organised in front of the C3 Hybrid Air prototype, on 5 March at 2:00 pm, 3:00 pm and 4:00pm and on 6 March at 10:00 am, 11:00 am and midday.

At Geneva, CITROËN is presenting Hybrid Air technology, a unique system developed by PSA Peugeot Citroën in cooperation with the Bosch® group and drawing upon the historic expertise of brand engineers in hydraulic systems for cars.

In 1955, with the DS, CITROËN launched a spectacular innovation: a system combining pressurised air with high-pressure hydraulics to control and manage the suspension, steering braking and semi-automatic gearbox.

In 1958, CITROËN engineers developed a prototype 2CV, a hybrid vehicle using pressurised air and hydraulics to boost the combustion engine. However, as there was no real market for the car, and technologies were lacking for its mass production, the project never became a reality.
In 2013, Hybrid Air technology is revolutionising the car industry.

Hybrid Air relies on proven sub-systems and technologies: a PureTech petrol engine, a compressed air energy storage unit, a hydraulic pump/motor unit and an automatic transmission with an epicyclic gear train. Eighty patents were filed by the PSA Peugeot Citroën Group during the development process An intelligent electronic management system manages input from the driver to optimise energy efficiency. Three operating modes are available:

• Air power, with zero emissions,
• Petrol power, using only the combustion engine,
• Combined power, with the combustion engine and hydraulic motor working together.


Breakthrough features

Adapted for a CITROËN C3 VTi 82, the Hybrid Air system slashes fuel consumption by one- third to achieve a record-breaking 2.9 l/100 km over a combined cycle, with CO2 emissions of 69 g/km. In urban driving conditions, the reduction in fuel consumption is around 45%.

Affordable technology with global reach

Hybrid Air technology uses no additional batteries, so could be sold at an attractive price on both European and international markets. The technology operates at a constant level of efficiency, regardless of weather or driving conditions. It could be developed not only in Europe, but also on all the other markets where the CITROËN brand is present. Easily adaptable for both passenger cars and LCVs, it is particularly efficient on B and C segment vehicles.

A technology that makes no comprises

The presence of the Hybrid Air system has no influence on interior space or boot capacity. The decision to opt for a system that is essentially mechanical simplifies servicing operations and makes for easier recycling at the end of vehicle life.

Real driving pleasure

Lower fuel consumption and CO2 emissions go hand-in-hand with significant improvements in driveability, thanks to:

• an automatic gearbox and epicyclic gear train with no break in torque,
• improved performance, with the additional torque and power available in Combined mode,
• a Stop&Start system using an alternator-starter.

System operation is smooth and completely transparent for customers,


Three operating modes for optimised efficiency

Hybrid Air is a coherent combination of several technologies. In operation, it relies on an intelligent electronic management unit to switch continuously between three driving modes. Optimizing energy efficiency in this way cuts fuel consumption and contributes to recharging the energy storage unit with compressed air.

Air mode
When Air mode is active, it works in the same way as ZEV mode on hybrid vehicles. The combustion engine is not used. The energy stored (compressed air) is transmitted to the wheels via the hydraulic motors and gearbox. Depending on traffic, this mode will concern between 60 and 80% of urban driving time. Maximum use of deceleration and braking energy will ensure efficient recharging of the compressed air unit. This mode is active up to 70 kph.

Petrol mode
Petrol mode transmits energy to the wheels without input from the compressed air unit. This mode is used primarily outside urban areas. Here again, the energy from deceleration and braking is recovered for the rapid benefit of ZEV mode or the boost function in combined mode.

Combined mode
In Combined mode, the combustion engine and hydraulic motor work together. This mode is used particularly during pick-up and strong acceleration, with a significant boost effect (total power of up to 90 kW) delivering a performance comparable to that of an engine in the next segment up.


The Geneva Motor Show will be an opportunity for visitors to discover the C3 Hybrid Air, a new step forwards in Créative Technologie. The prototype on show features a number of specific characteristics including:

• new Michelin® tyres with specific sizing (165/50 R 18) that cuts fuel consumption by
almost 0.2l/100km. This tyre has a particularly large diameter and reduced width for
lower rolling resistance, weight and noise,
• specific colours and materials, with anis-tinted wheels, exterior door mirror housings and
headlight slats.
This prototype is swept from front to rear by a "car scan" function, showing the workings of Hybrid Air technology. A tool reflecting the spirit of the brand's Créative Technologie.

CITROËN already markets a range of advanced technologies for all types of use:
• Hybrid4 diesel hybrid technology available on the DS5 (25% of versions sold in Europe in
• full electric with the C-ZERO city car and Berlingo LCV, available during the second quarter
of 2013,
• e-HDi micro-hybrid technology, the most well-rounded system on the market, combining
comfort and efficiency, and available on most brand models, for example: the e-HDi 70
engine on the CITROËN C3, which emits just 87g of CO2,
• and PureTech, a new family of cleaner, more powerful petrol engines, increasing power by
15% and cutting fuel consumption/CO2 emissions by 25% compared with the previous generation of petrol engines.

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    • 1 Second Ago
      • 2 Years Ago
      Wouldn't KERS be better than this....Anyone?
      2 wheeled menace
      • 2 Years Ago
      With the right battery of the right size, you can soak in 100% of the braking power. An EV with a Toshiba SCiB battery could do this as of now. A supercapacitor can do the job with slightly less power loss on the way in, but a modern battery can do it now. My ebike does half it's braking on the back with a hub motor, on a battery that isn't all that large. A car could do 50% regen today to the drive wheels.
      • 2 Years Ago
      I'm not that familiar with the specifics of battery tech, so I could use someone explaining the details to me. But I was under the impression that you cannot rapidly dump regen energy into a chemical battery (at least not as fast as the regen system is generating it). So when you are stepping on your brakes in an EV, at least a portion of that energy that is being recaptured has to be expended as heat. A compressed air system would theoretically be able to absorb more of that energy in the same time frame. Or at least that is my understanding from reading about it but not actually working with either tech.
      • 2 Years Ago
      I didn't say they can't capture regen. They capture less regen. I am not going to dig it up right now, but the numbers I read previously show hydraulic accumulator capture more than double the regen energy of a typical electrical hybrid. This is really the reason to go with this system it should be even more efficient than regular HEV in stop and go driving.
      • 2 Years Ago
      Very clever, if it can be made commercially viable.
      • 2 Years Ago
      Arguments that this is somehow better energy storage than batteries fall completely flat. This is using a hydraulic accumulator for storage and for energy density there is no contest, batteries store about 50 TIMES the energy mass vs mass. I also doubt there is really a cost advantage. The advantage comes in form of regen capture. Batteries are limited in how large of a pulse of energy they can absorb, where the accumulator can absorb a much greater pulse of energy, capturing more regen energy for each braking event. The total storage capacity of this system is likely VERY low, much less than a standard Prius. So it best serves those who spend a lot of time in stop and go traffic.
        2 wheeled menace
        • 2 Years Ago
        Oh, batteries can't take regen pulses? Tell the owners of Toyota Priuses that.... ;D The NiMH in the Priuses works great, and is rather wimpy as a matter of fact, compared to batteries such as 10C-20C charge capable lithium titanate and 'nanotech substrate' lithium cobalt. The advantage that a hydraulic accumulator has is cost and longevity. But really, 1 kilowatt hour worth of compressed air is going to be huge in size and pressure - i can't visualize how large it is, but it's huge... and you've got safety issues... Imagine one of these tanks under super high pressure being punctured / blowing a seal and catapulting the car!
      Giza Plateau
      • 2 Years Ago
      Computer says no.. Not gonna happen
      • 2 Years Ago
      "An air hybrid car should also be cheaper than a similar vehice with a standard hybrid powertrain." They always say that at this stage of early renderings.... then they do a full analysis... and determine that a small battery is not that expensive after all. Really this is a design for capturing patents.
      • 2 Years Ago
      Typo in the title
      • 2 Years Ago
      There are other things to consider other than price 1) It may be more environmentally friendly to use this system rather than batteries 2) This system might perform better in extreme temperatures than batteries that suffer range loss 3) Improved cargo space, as suggested by the article 4) May be more practical for larger vehicles than batteries 5) EVs suffer from long "refueling" times, even with powerful charging stations
        • 2 Years Ago
        Also compressed air systems have a lower efficiency than batteries. So this hybrid system is not a stepping stone to plug-in or fully emissions free vehicles. The compressed air acts like a flywheel storing energy temporarily to improve mileage in stop and go traffic.
        • 2 Years Ago
        I think that it is worth noting that air compressed at higher temperatures will provide less energy if the vehicle is cooled so the efficiency of this system could be affected by cold temperatures.
        • 2 Years Ago
        Um.... this is NOT a plug in vehicle. This is NOT comparable to a BEV or PHeV. This is a comparison for conventional hybrids.... which, are not affected by extreme temperature very much. There is no loss of range. There really is no environmental concern either. Hybrid batteries don't take up too much space either. We'll see if they can get this system working as cheaply as Toyota has made their line of Hybrids.
          • 2 Years Ago
          I didn't say it was a PHEV, I know its not, but if the system can nearly achieve the mpg equivalent of a PHEV I thought it was worth making some comparisons.
      • 2 Years Ago
      Battery cannot take it as good as other medium, like supercapacitor. I think the competitor is not battery but supercapacitor.
      • 2 Years Ago
      I'd love to see the SCiB fully utilized in either an EV or plugin hybrid.
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