A DEVICE developed for motor racing is being used by BMW to streamline two new models.

The latest versions of the 1 Series coupe and convertible - due on sale at the end of March - will feature a system to reduce drag around the front wheel arches.

The Aero Curtain works by channelling air into two ducts in the front apron which then flows out of a narrow opening at high speed in the wheel arch. The jet of air then covers the side of the front wheels like a curtain reducing turbulence.

Wheel arches are a major source of drag which impacts on a car's efficiency but with the Air Curtain in place BMW says the aerodynamic improvements make the cars more slippery with lower CO2 emissions.

The entry level diesel engine 118d Coupe, which will cost from £21,960, now has a CO2 output of 118g/km and all two-litre petrol versions have a CO2 figure below 155g/km - an improvement of more than two per cent compared to the current models.

As well as the Aero Curtain, which will be fitted on ES, SE and Sport trims, the new 1 Series coupes and convertibles feature restyled front and rear lamps and a new look front bumper.

Convertible models will be priced from £24,245 when the new range goes on sale on March 26.