BMW is launching the third generation of the benchmark four-seater 3 Series Convertible this month, just in time to make the most of summer, writes David Duffy.

It is the fourth model in the much praised E46 3 Series range, joining the saloon, coup and Touring, all of which are enjoying great success in their respective markets. The new Convertible offers a host of new features to make soft-top motoring more practical and safer, as well as stylish and sheer good fun.

One model is available initially, the 170 horsepower BMW 323Ci, which will be joined by the new 231 horsepower 330Ci in July.

Previous incarnations of the 3 Series Convertible have become firm best sellers in the growing market for practical convertibles, securing over 30 per cent of the sector.

The roof for the new 323Ci is triple lined for insulation and electrically operated as standard. It folds in 25 seconds, which is quicker than any competitor, and is concealed beneath a neat cover. It is equipped with a heated, scratch-proof glass rear window, addressing one of the few criticisms of previous 3 Series Convertibles.

Unique to the new BMW 3 Series Convertible is the collapsible roof cartridge which contains the roof when it is down. This sturdy, waterproof cartridge can be folded up when the roof is raised or removed to provide 40 litres more boot space (total 300 litres).

A factory-painted matching hard top is available too. It has a heated rear window, front grab handles, shaped roof lining, rear courtesy lights and costs 1,595. The interior of the 323Ci boasts a range of features unique to the Convertible a new three-spoke sports, multi-function steering wheel and a new seatbelt system that provides better fitting of the belts to the body, stops them flapping and allows easier access to the rear, as does a switch at the top of the backrest which moves the seat forward at double its normal speed. The 323Ci with five-speed manual gearbox is priced at 28,995 or for a further 1,220 a five-speed automatic transmission with semi-automatic Steptronic operation can be specified.

The launch of the new car comes after BMW posted an all-time record sales result for the month of May.

Even before the final figures closed, more than 5,800 new BMWs were sold during the month, more than 17 per cent than the previous highest May sales of 1999.

Jim O'Donnell, BMW GB's new managing director, said: "BMW's result in May proves that prestige cars remain highly desirable."