2010 BMW Z4- two models become 1

With its first redesign since being introduced in 2002, the 2009 BMW Z4 roadster looks as if it's finally passed through its awkward adolescence and has filled out into a curvaceous hardtop roadster.

The most obvious change to the Z4 when it debuts at the Detroit auto show in January will be its more conventional styling. The polarizing influence of Chris Bangle has been greatly toned down, although the trademark "Bangle butt" remains. Overall, the lines look similar to those of the BMW 1-series, though some cues carry over from the new 7-series as well.

The other plainly clear difference is the absence of a cloth top. In lieu of separate convertible and coupe variants, the new Z4 features a retractable hardtop that disappears at the touch of a button within 20 seconds. Less clear from the pictures are the Z4's stretched dimensions. The new car is nearly 6 inches longer and a half an inch wider than its predecessor. BMW says this growth affords passengers more comfort and space inside. The larger size, coupled with the addition of the power-operated hardtop, contribute to a weight increase of roughly 500 lbs in a fully loaded, automatic model, to a claimed curb weight of 3494 lbs.

Changes inside are a bit subtler. The biggest news is the availability of iDrive for the first time in a Z4. Overall, the interior appears to have moved decidedly more upscale, especially when equipped with the optional leather-wrapped dash. BMW says it focused on increased practicality as well. Door openings are larger for easier ingress and egress, and there are new storage compartments throughout the interior. In the trunk, a mid-gate separating the roof compartment can be folded down for more luggage. An optional winter package adds a pass through to the cabin, allowing room for up to two full size golf bags with the top up, BMW says.

Under the hood, the Z4 features a pair of revised 3.0-liter inline-sixes. The sDrive30i comes with a naturally aspirated version of the engine producing 255 hp, compared with 215 hp in the current base Z4. Top-level, sDrive35i roadsters will receive the 300 hp, twin-turbo six used in the 335i. The sDrive30i comes with a choice of a six-speed manual or automatic, while the sDrive35i adds the option of BMW's seven-speed dual-clutch transmission. BMW estimates the dual-clutch transmission equipped, turbocharged model will go from 0 to 60 in 5.0 seconds.

At the moment, BMW has no plans for an M-model. Our man in Europe, Georg Kacher, indicates the reason is BMW can't fit the M3's V-8 into the Z4's engine bay. He adds that we might see some four-cylinders to the lineup in the near future.

Little has changed in the roadster's suspension, which retains the traditional strut front, multi-link rear configuration. Z4s equipped with the optional Sport Package get electronically adjustable dampers. Drivers will also be able to configure throttle and steering response, stability control, and the shift points on the automatic transmission.

The Z4 will launch late in the second quarter of 2009, just in time for summer. BMW has yet to release official pricing information, but expect the increased accomadations and the hardtop to add about $5,000 to $10,000, depending on the trim, meaning a base price around $40,000 for the sDrive30i and $50,000 for the sDrive35i. Stay tuned for more information.