BMW launches its smallest four-seater convertible on April 5, and the stunning new 1 Series cabrio promises to be one of the must-have soft-tops for this summer. Initially available with BMW's renowned 120i and 125i engines, the range will almost immediately be extended with the introduction of the 118i, 120d and 135i models. While the 120d is the most economical in the range, achieving 55mpg, the two six-cylinder 125i and 135i models deliver scintillating performance with the 125i producing 218bhp and the 135i an explosive 306bhp.

In a break with current convention, the 1 Series cabrio has a fabric roof rather than one of the heavier folding metal roofs. The electrically-powered roof can be raised or lowered at speeds up to 31mph which means you should never be caught out by a surprise summer shower!

Oh, and if the sun does shine, all leather-upholstered car come as standard with BMW's innovative SunReflective leather technology. This helps keep the surface temperature of the upholstery on a hot day up to 20 degrees centigrade lower than a normally-upholstered leather seat.

Prices for the 1 Series cabrio - available in three specs, ES, SE and M Sport - start at £22,335 for the entry-level 118iES which produces 143bhp, hits 62mph from standstill in 9.3secs, has a max of 130mph and has fuel figures of 44.8mpg.

The range tops out at £32,415 for the 135i M Sport (306bhp, 5.6secs, 155mph and 30.1mpg), with the diesel 120d - which is expected to account for around 20% of sales in Scotland - starting at £24,860 for the ES (177bhp, 8.1secs, 138mph and 55.4mpg).

"Our engine line-up ensures we have been able to maintain our reputation for class-leading efficiency without impacting on BMW's renowned history for delivering performance machines," Ollie Parsons, 1 Series product manager, told Phoenix News. And 1 Series cabrio designer Kevin Rice took time out from the car's launch in Jerez to explain his reasons for not including a metal folding roof.

"It was always going to be a soft-top," Rice explained, "because we had to retain the high side shoulder line which emphasises the car's aggressive look. It was also crucial in maintaining the car's elegant and sporting feel. "We've worked hard with the acoustics of the roof, which follows the line of the 1 Series Coupe almost identically, to ensure the cabin is a calm and peaceful place to be when it's in place."