A one-off show car boasting a fuel consumption figure of 2.0L/100km is nothing new, but unexpectedly, Citroen's C4 Cactus Airflow 2L is not a plug-in hybrid.
The concept will be appearing at next month's Paris motor show, complete with optimised aerodynamics, lightweight materials, a frugal internal-combustion engine – and Citroen's own 'Hybrid Air Technology'.
Based on the C4 Cactus, but 100kg lighter, the concept car is claimed by the manufacturer to be 20 per cent more efficient, aerodynamically, and 30 per cent more economical. Air flow is automatically adjusted to allow added engine cooling as required, or reduce drag at higher speeds. Other aerodynamic enhancements include rear-facing cameras in lieu of exterior mirrors and the adoption of LED lights in place of conventional lighting.
The 19-inch wheels have their own shutters, which are opened or closed by centrifugal force to reduce turbulence. And those same wheels are wrapped in tyres specifically designed to reduce rolling resistance and conserve fuel and energy in accordance with precepts devised by the Plateforme de la Filière Automobile industry group in France for a car to consume just 2.0L/100km.
Lighter materials selected for the C4 Cactus Airflow 2L include aluminium for structural members, high-strength steel, carbon fibre, translucent polycarbonate for the panoramic sunroof and composite material for the front floor, springs and body members. Weight savings were also made by narrowing the tubes and cups in the exhaust. The 100kg weight reduction (11 per cent lighter than the standard C4 Cactus) brings the concept car's kerb mass to 865kg.
Citroen's Hybrid Air drivetrain – making its debut in a Citroen C3 at Geneva last year – has been carried over to the C4 Cactus Airflow 2. A three-cylinder petrol engine is combined with a compressed air storage system with motor, a hydraulic pump and a conventional automatic transmission. Three operating modes for the car are: Air power, petrol power and combined power. Already powering the conventional C4 Cactus, the PureTech 82 three cylinder engine has been tweaked for maximum fuel efficiency in the concept car application. Optimised combustion, in alliance with lower internal friction losses – through diamond-like carbon coating, polymer pads and low-viscosity oil – has yielded efficiency gains of five per cent. In conjunction with the Hybrid Air system the efficiency of the motive power sources is improved by 30 per cent.