BMW 3 Series Convertible Preview – 2007 Detroit Auto Show: Flinging a great car down a great road is great fun, even more so when the top is down to heighten the sensation of speed. Few cars on the market today can provide this kind of thrill for a driver and three passengers quite like the BMW 3 Series Convertible. For 2007, the 3 Series Convertible is redesigned, getting a power retractable hardtop for the first time. Two versions with different engines are available: the 328i and 335i.