BMW and Audi have revealed details of their new convertible models, both of which go on sale next spring.

The BMW 3-series Convertible, due to make its world debut at the Detroit show in January, features a folding metal hard-top that is divided into three pieces to make it more compact when stowed. The electrically-operated roof turns the four-seat model from coupe to opentop in 22 seconds.

The range features a choice of five engines – the twin-turbo 335i with 306bhp, 330i with 272bhp, 218bhp 325i, a 320i offering 170bhp and a 330d diesel producing 231bhp. Prices are not yet announced.

Over at Audi, the roof has come off the new TT range to create the Roadster. With a turbocharged 2.0-litre engine with 200bhp or 3.2-litre V6 quattro with 250bhp, the new model has a fabric roof and costs £26,915-£31,535.

BMW 3-series convertible video