BMW's redesigned 2009 Z4 roadster is the company's first to come with a retractable hard top roof. Other new features includes a double clutch automatic transmission and a hard disk navigator/entertainment system. Unlike its predecessors, this one will be built in Germany, rather than the US.

The new line goes on sale early in 2009 with cars reaching the key right hand drive UK market in May.

The two-piece, electro-hydraulically operated roof can be raised or lowered in 20 seconds. The new roadster is also the first vehicle to be offered with 'Adaptive M' suspension. Electronically controlled dampers offer three different configurations and lower the ride height by up to 10mm for a more dynamic drive. By way of comparison, the Sport+ setting of the new car is comparable to the outgoing Z4's standard ride comfort level.

The standard Drive Dynamic Control function is another first and allows the driver to alter, depending on model specification, the throttle and steering response, level of ride comfort, Dynamic Stability Control response and, on automatic or Double Clutch Transmission cars, gear change times.

The initial engine choice is three six-cylinder (I6) units topped by a three-litre twin-turbocharged engine producing 306hp at 5,800rpm in European tune (Z4 sDrive 35i).

The launch line-up also includes sDrive23i and the sDrive30i versions. The 2,497cc entry-level car has 204hp and the sDrive30i comes a 2,996cc powerplant developing 258hp.

A six-speed manual gearbox is standard and the two smaller engines have an optional six-speed conventional automatic transmission with gear change paddles on the steering wheel. The sDrive35i offers the more advanced seven-speed double clutch transmission, also with gear shift paddles on the wheel.

The redesigned Z4 has BMW's fuel consumption and emissions-reducing EfficientDynamics package including brake energy regeneration, electric power steering with servotronic, reduced rolling resistance tyres, on-demand control of the engine's ancillaries and optimum shift indicator on manual transmission cars. The front suspension and subframe are largely made from aluminium.

The new model is larger than its predecessor: 148mm longer at 4,239mm and 9mm wider at 1,790mm, and this results in greater interior space and luggage capacity. With the roof up, headroom has been increased by 44mm and there is 20mm more shoulder room and 43mm more elbow room.

New is a storage facility behind the seats. This approximate 15.5-litre single compartment stretches the width of the car's interior and has a net to hold contents in place. It can be complemented by an optional storage package.

The latest iDrive is used and the optional Professional Multimedia Navigation system has a hard disc drive with 12Gb of audio file storage and ConnectedDrive functionality. The system also comes with eight programmable Favourite buttons as system shortcuts.

The boot varies in capacity from 180 to 310 litres - large enough, BMW says, to stow a full set of golf clubs. Buyers also can now order a through-loading system for additional storage capability. A hatch between the two seats permits a second full set of golf clubs to be carried.

Side visibility is up 40% and the glass rear window improves visibility by 52%.