BMW Z4

BMW has redesigned its roadster for 2009, and the change amounts to comprehensive maturation, if not quite the obvious transformation from newborn Z3 to adolescent Z4.The new two-seater retains the name Z4, but it adopts two clumsy new model designations, the sDrive30i and sDrive35i. You'll notice there's no M roadster anymore, and word is that none is forthcoming. Nor will we see a return of the historically slow-selling hatchback coupe variant.

The previous entry-level, 215-hp in-line six is history, and the old car's more powerful 255-hp, 3.0-liter powerplant is now found in the base Z4 sDrive30i. Meanwhile, the twin-turbocharged six that we know and love from the 335i and the 135i puts 300 hp under the hood of the Z4 sDrive35i. We had a chance to sample the latter model,equipped with a seven-speed dual-clutch automatic transmission, a variant of the BMW M3's M DCT gearbox. Appearing in the Z4 for the first time, this transmission is exclusive to the turbocharged car. The base Z4 offers a conventional, six-speed automatic (with shift paddles); both Z4 models come standard with a six-speed manual.

With thirty fewer horses than the old M roadster-which used the 330-hp six from the previous-generation M3-the sDrive35i can't match that car's frenetic persona. But the twin turbo makes 38 lb-ft more torque, so acceleration isn't far off. The factory-measured 0-to-6o-mph time is 5.o seconds (add 0.1 second for the manual gearbox), versus 4.9 for the old M roadster. The blown six is pretty sweet in its own right, its turbos so seamlessly integrated, its torque band so wide, and its power delivery so linear that a driver might never suspect it is turbocharged.

Pairing it with the new dual-clutch gearbox may help wring out the last tenth of the engine's performance-there's even a launch control mode-hut it's not as involving as a true manual. Strangely, the steering-wheel-mounted shift paddles do not follow the same logic here as they do in the M3. where one paddle upshifts and the other downshifts. Instead, either paddle can shift up (by pushing forward) or down (by pulling hack)-the idea being that the Z4 can be shifted with only one hand on the wheel, whereas the more serious M3 pilot is someone who drives with two hands.

Of course, the Z4 driver is also highly likely to simply slap the lever into Drive, in which case the dual clutch gearbox commendably emulates the smoothness of a conventional, torque-converter automatic, particularly in stop-start-and-reverse maneuvering. Even in D, instant downshifts are still available at the push of a paddle. The transmission eventually will return to Drive: to hold a gear, the lever must be in the manual gate-all of which is pretty standard, and logical, practice.

Flexibility is a hallmark elsewhere in the Z4 as well. A console mounted switch toggles among three settings: normal, sport, and sport-plus, effecting changes in the steering effort, in throttle mapping,in the shift logic of the automatic transmission, and in damper firmness. (The latter is only for cars equipped with M Adaptive damping, part of the sport package, which also includes sport seats,eighteen-inch wheels, and a more generous electronically limited top speed of t 50 mph rather than 130.) This is a further evolution of the optional Sport button in the previous Z4, which affected throttle,steering effort,and automatic transmission shift control.

Carmakers' attempts to create electronics induced multiple personalities have become increasingly widespread, but we find that they're often of little value. In the case of the Z4, the range from normal to sport-plus is pretty narrow. The difference in throttle napping, for instance, is barely discernible,although that's rather a blessing since a hypersensitive gas pedal does not make a responsive car.

The change in steering effort is more notable, switching from too light to just right-but we'd happily do without the former.The steering is again electrically assisted (although the M roadster used hydraulic assist), and it's certainly precise but lacks that last measure of tactility.

With regard to the transmission, we ended up preferring the less aggressive modes. All are responsive to a quick stomp on the throttle, but in sport-plus, the gearbox is so reluctant to upshift that you end up cruising around in fourth gear when a mellower mode would select seventh.

The selectable damping is a new feature with this redesign. Again, the differences among each mode are subtle. But when driving hard, you appreciate the extra control of body motions (primarily squat and dive) offered by sport-plus, which combines with firmer steering to create the most confidence inspiring overall setup.This was our preferred setting for attacking the endless series of switchbacks on our test route. Sport-plus also loosens the reins of the otherwise overactive stability control (and illuminates its warning light on the dash),allowing a welcome bit of rear slip angle. But it would take real determination, and the stability control switched off completely, to unstick the rear end. Even in sport-plus, the chassis has so much grip-on its wide Bridgestone Potenzas-that the Z4 proves endlessly forgiving, never twitchy.

One important question is how much ride comfort is sacrificed with the firmer setting,and the answer is none-provided you're on unblemished pavement like that in sun kissed southern Spain, where we conducted our test drive. As long as the ride in less idyllic conditions isn't too brutal, it's frankly hard to see the need for the other settings.

A second major aspect of the new Z4's attempt to expand its appeal is the switch to a retractable hard top. Not only does this mean a power top is now standard, but the sense of claustrophobia with the top up is greatly diminished thanks to the hard top's slim C-pillars and the addition of rear quarter windows. On the downside, a retractable hard top usually weighs more than a soft top and eats up more trunk space when stowed. Indeed, the L4 has gained about 200 pounds, but top-down trunk space has shrunk only slightly, to a still-usable 6.4 cubic feet. Top up, the trunk is significantly larger than before.

The hard top crowns an all-new exterior that sees the previously gawky styling transformed into a striking and handsome new design. The skillfully reshaped sheetmetal is stretched almost six inches in overall length and fractionally in width.The cabin is again set well back in the car,creating a cab-rearward, old-school roadster feeling. You look out over the long, stylized hood, and in front of you is a curving, swept away dash, which faintly recalls the BMW Z8.The passenger compartment has a bit more elbow room than before and, in our test car, was dressed in optional Nappa full-leather trim, with materials quality that
was above reproach. The new cabin also boasts additional stowage, but the cupholders are awkwardly located under the center armrest. BMW's iDrive makes its first Z4 appearance here (with the optional navigation system), and this latest version,with more dedicated buttons making for less menu surfing, now actually borders on user-friendly.

A quick look at the sticker prices suggests that BMW has in effect dropped the entry level Z4 (which last year started well under $40,000) and that the two versions of the new car roughly match up against the
previous uplevel Z4 and the M roadster. The new Z4 sDrive35i may not have the purity of the old M roadster, but it essentially equals its straight-line performance, and its handling is even better. We might not be totally convinced by all the electronically changeable elements, and we might prefer the standard manual transmission, but we're happier in the new cockpit, and we gratefully welcome the new exterior design. With this latest generation, the modern BMW roadster takes another step on its way to becoming a sports car classic.

Automobile Magazine june 2009