This is the Citroen C4 Cactus Airflow 2L Concept, which is set to debut at this year’s Paris Motor Show. Since times are a changing, 2L in this case does not refer to a 2.0 litre engine under the hood, but actually refers to the car’s target of a two litres per 100 km fuel consumption.

Citroen says this has been achieved by an optimised exterior design with a 20% improvement in aerodynamics, including air intakes that have variable openings, wing mirrors that have been replaced by slimmer rearview cameras as well as tall and narrow 155/70R19 tyres with lower rolling resistance. It’s lighter too, with carbon composites, polycarbonates and aluminium parts contributing to a 100 kg decrease in overall vehicle weight.

There’s also the implementation of Hybrid Air technology, which also appears in the Peugeot 208 HYbrid Air 2L. The Hybrid Air powertrain combines a 82 horsepower 1.2 litre petrol engine with a compressed air hydraulic system which is used to assist and even replace the petrol engine to enable maximum efficiency during acceleration and starts.

The system is made up of a compressed-air tank located below the boot, a low-pressure tank near the rear axle acting as an expansion chamber and a hydraulic system consisting of a motor and a pump in the engine bay. Power goes to the wheels via an epicyclic geartrain which offers automatic operation.

For more on how the system works, read our 208 HYbrid Air 2L story.