2009 BMW Z4 Roadster

After a couple years of speculation, BMW is finally unveiling its all-new Z4 Roadster at the Detroit Auto Show. The new Z4 is slightly larger and slightly heavier, yet more luxurious and with a more user-friendly cabin. BMW calls the occasion of new Z4's launch "the rebirth of the roadster."

The Z4's body has been given an elegant redesign, but the most noteworthy aspect is a two-piece aluminum (and power-operated) retractable hardtop. The top opens or closes in 20 seconds, yet BMW says trunk space has not been compromised.

The new Z4's wheelbase has grown by only 0.1 in., but the car itself is 5.8 in. longer and 0.4 in. wider than the outgoing model. The return for this is increased passenger space, with 0.2 in. more head room, 0.8 in. more shoulder room and a whopping 1.7 in. more elbow room. The door openings were also increased by an inch to aid with ingress/egress, while all-around outward vision has improved. The downside to the car's increase in mass is…its increased mass — the curb weight of the base model is up by about 200 lb., to 3240 lb.

The interior has been completely overhauled. It's far more stylish yet also more user-friendly, thanks to the adoption of several new (and needed) storage cubbies. The HVAC controls are new, and the Z4 will now be available with iDrive for the first time (part of the optional navigation package). The nav/iDrive's 8.8-in. high-resolution display screen retracts into the dashboard when not in use.

Formerly the top engine for the Z4 (Z4 M Coupe/M Roadster notwithstanding), the 255-bhp 3.0-liter normally aspirated inline-6 becomes the base engine for the model known as the Z4 sDrive30i. The new top-shelf engine is BMW's well-known (and well-loved) twin-turbo 3.0-liter inline-6 with 300 bhp and 300 lb.-ft. of torque. This car becomes the Z4 sDrive35i. Both models come standard with a 6-speed manual transmission, which BMW says features the shortest throws of any car they make. The sDrive30i is also available with a 6-speed automatic, while the sDrive35i can be fitted with a 7-speed version of BMW's new twin-clutch M DCT transmission. Both the 6-speed automatic and 7-speed twin-clutch gearboxes come with steering-wheel-mounted paddle shifters.

BMW claims the twin-clutch Z4 sDrive35i outsprints its 6-speed manual brother by 0.1 sec to 60 mph (5.0 vs. 5.1), while the manual-equipped sDrive30i hits 60 mph in 5.6 sec vs. the automatic's 6.0.

Dynamic Drive Control will be standard, this feature allowing the driver to choose among three settings (at the touch of a button on the center console) for throttle control mapping, engine management, stability control response and the electric-assist power steering.

Our only question is this: By naming the models Z4 sDrive30i and Z4 sDrive35i, could BMW have made the designations any more cumbersome?