The Citroen concept is said to offer fuel consumption of just 2.0 litres per 100 kilometres (hence the 2L), by combining a three-cylinder petrol engine to a compressed air energy unit. The drivetrain allows the C4 Cactus to run in three modes: Air power, using the compressed air housed in the tanks under the boot floor; Petrol power, where only the engine is used; and Combined power, which calls on both motors. Read more about how Citroen's compressed air system works here.
Further changes to help the car achieve the 2.0L fuel use claim include revised design features such as side cameras rather than larger mirrors, active air intakes and active wheel shutters to improve aerodynamics by 20 per cent, and "tall & narrow" 19-inch low rolling-resistance tyres.
Citroen says it has managed to cut 100 kilograms out of the car - making its unladen kerb weight a diminutive 865kg - by replacing underbody parts: aluminium has been used for the upper cowl, inner side members and rear floor pan; high-yield steels have been used for the front side rails and heel board; and composite plastic is used for the floor at the front of the car.
Further lightweight materials have been used, including carbon composite suspension springs, tailgate, doors, roof and side panels, and a polycarbonate panoramic roof which saves a few grams over a conventional glass unit. Carbonfibre has even been used in the Air Bumps on the side of the car.
"A laboratory for new ideas, the C4 Cactus Airflow 2L is packed with advanced technologies that illustrate the ambition and ability of the brand to develop innovative responses to the automotive challenges of the present and the future," a release from the brand said.
"All these advanced technologies together deliver consumption of 2.0L/100 km. It could therefore be possible, in the medium term, for a production vehicle such as C4 Cactus to reach this target."
While that's hardly confirmation the brand will offer a production version of the car, PSA Peugeot Citroen has previously stated its intent to offer a hybrid air car to market by 2016.
And it's not the first time Citroen has played with the idea of a car that can run on compressed air - indeed, the original C4 Cactus concept was fitted with a similar propulsion system. The brand also showcased the C3 Hybrid Air concept in 2013, while sister brand Peugeot will also show off a new air hybrid vehicle at the Paris show with its 208 Hybrid Air 2L.
The new concept car will debut at the 2014 Paris motor show in early October.
The regular petrol-powered Citroen C4 Cactus is currently said to be under consideration for Australia, though a representative previously confirmed the funky crossover would be sold here.