VIDEO REVIEW:
http://reviews.cnet.com/convertible/...html?tag=mncol
The good: The BMW Z4 sDrive35is' adaptive suspension responds well whether cruising through the city or carving the canyons, and the dual-clutch transmission makes fast shifts. Available cabin tech includes an excellent navigation system.
The bad: The retractable top folds into the trunk, which limits cargo capacity and messes with the weight distribution. The transmission's sport setting could be more aggressive.
The bottom line: Although not as hard-edged as some sports cars, the 2011 BMW Z4 sDrive35is provides plenty of driving fun and, except for the lack of cargo capacity, makes a fine daily driver.
BMW must think its recent cars strayed too far from its sports car ethos, as it is bringing back the "s"--denoting sport--to select models. We previously reviewed the 2011 BMW 335is, and now get a look at the new sport roadster, the 2011 BMW Z4 sDrive35is.
This roadster comes loaded to the gills with BMW's performance technology, all surprisingly standard for a company that charges extra for every little convenience feature. But the Z4 sDrive35is also makes a few compromises for comfort that undercut its sporting nature.
The Z4 is a good-looking little roadster, and we noted a lot of attention from bystanders. Its retractable hard top is a best-of-both-worlds solution, offering the security and weather protection of a hard top plus the fun of open-top driving. The top folds into the trunk with Transformers-like mutability.
The retractable hard top is a miracle of engineering.
The retractable top doesn't come without consequences, however. First of all, when folded away into the trunk there is very little storage space left, and what there is can be explored only with the type of robotic equipment being used on BP's Gulf oil gusher.
And although BMW takes its sports car dynamics very seriously, the retractable top throws off the car's balance one way or another. If BMW engineered the car for a 50/50 weight distribution with the top up, the front will be light with the top down, and vice versa. A soft top would have had less impact on the car's weight distribution.
BMW compensates for the weight change with its dynamic suspension, an option on just about every other BMW car, including the M models, but standard in the Z4 sDrive35is. When set to Sport or Sport Plus, the suspension lowers by almost half an inch. This suspension uses sensor input to adjust each of its dampers independently, making them softer or more rigid depending on the road and what the driver is asking of it.
These buttons cycle through Normal, Sport, and Sport Plus modes.
As with other recent BMWs we've tested, the Z4 sDrive35is exhibits a dual character; it's perfectly comfortable to drive over a variety of roads on a daily basis, and is willing to get down and act mean on a track or in the twisties. In Normal mode, the suspension is loose and compliant, but far from soft. Going to Sport or Sport Plus mode, we didn't notice a sudden, dramatic difference, but the car becomes more rigid.
We threw the Z4 sDrive35is into corner after corner, finding that it offered so much grip and such good control that we could maintain very high speeds. The car encouraged us to push harder and harder, and we were impressed by how well it stuck to the pavement, without allowing much of the tail wag that larger BMWs use to rotate in a turn.
But getting close to the limit, we repeatedly found understeer; the car headed toward a wall or cliff instead of going in the direction we pointed the wheels. This was surprising, and not something we would expect in a BMW. As it happened with the top up and down, we ascribe it to BMW finding a less-than-perfect compromise to the moveable top's weight distribution changes.
Twin turbochargers
Along with suspension settings, the Sport and Sport Plus modes put the throttle at a more aggressive level, the latter also turning down traction control. The Z4 sDrive35is gets the same engine as the 335is, a 3-liter direct-injection straight-six with twin turbochargers. Each low pressure turbocharger forces air into a set of three cylinders.
M sport wheels come standard on the Z4 sDrive35is.
Tuned for the Z4 sDrive35is, this engine produces 340 horsepower and 332 pound-feet of torque, which is significantly more than the standard Z4's 306 horsepower. And like the 335is, the Z4 sDrive35is has an overboost feature, which temporarily pumps the torque up to 369 pound-feet, putting 0-to-62 mph acceleration at 4.8 seconds.
The exhaust note was higher pitched than that of the 335is, and was not to everyone's liking on the Car Tech staff. It is quite distinct.
Another surprising standard feature is the seven-speed double-clutch transmission (DCT). A traditional manual transmission is not even available in the Z4 sDrive35is.
In standard drive mode, the DCT reaches for the gas-saving higher gears, and feels a lot like an automatic transmission. In Sport mode, it keeps the engine revs higher, and shifts down a little more aggressively, but not enough for our tastes. Powering out of a corner, the DCT had only dropped down to fourth gear, leaving the engine far from peak power at 3,500rpm.
Manual mode was the only choice for real sporting performance out of the Z4 sDrive35is. Using the paddle shifters, we could take it down to third or even second, letting the tach spool up to 5,500rpm, snapping gear changes out in quick succession.
We are used to BMW's weird-looking gearshifts, but that has not endeared us to it. Both the console shifter and the paddle shifters incorporate the same weirdly organic design, which is not in keeping with any other aspect of the car.
The shifter and paddles look more like a product of artists than engineers.
As a final piece of performance tech, if anyone remains skeptical about electronic power steering, the Z4 sDrive35is should erase all doubt. The wheel felt good, always offering good road feedback as we slung the car over our favorite roads. It also provided a comfortable amount of boost when we pulled parking maneuvers in the city.
Another useful perk, especially for negotiating the hills of San Francisco, is a hill-hold feature that kept the brakes on as we went from brake to gas pedal.
Although a small car, the big engine means fuel economy of only 17 mpg city and 24 mpg highway, according to EPA tests. In our driving, in which we spent a lot of time pushing the car hard, we turned in an average of 19.2 mpg--not too bad for the Z4 sDrive35is' level of performance.
Little extras
BMW's are not known for lush luxury, but they still employ excellent fit and finish for their fine cabin materials. In the Z4 sDrive35is, the leather is thick and the plastics are soft. We like the comfort of the sport seats and the thickness of the steering wheel.
Of course, with a base price of $61,050, we would expect a high-quality interior. Our car's final price was not much above base, as it had very few cabin tech options, just iPod integration, satellite radio, and keyless start. There were buttons for voice command and phone, but these were not active, as the Bluetooth phone system was not optioned. Given the high base price, BMW could probably have thrown in the phone system standard.
But BMW does make a good range of cabin tech available in the Z4 sDrive35is, and we have used similar features in other BMW cars. The hard-drive-based navigation system responds quickly and offers richly detailed maps. The Bluetooth phone system downloads a phone's contact list, and in more recent models offers dial-by-name voice command.
BMW makes it possible to browse an iPod library on its radio display.
As our car lacked navigation, we were left with the monochrome radio display for browsing our attached iPod's music library. BMW is fairly clever in using this limited screen real estate. We could select genre, artist, or album, and then scroll through the ensuing lists to find the music we wanted. However, other companies have managed to put larger displays into their cars to handle increased information demands, and it's time BMW caught up with this trend.
A premium audio system is available, but our car had the stock six-speaker system. Comprised of two tweeters, two mids, and two woofers behind the seats, the sound quality is much better than that found in most six-speaker systems. As is typical for BMWs, a powerful amp gives music a very strong sound, especially useful for driving with the top down. Bass and mid detail is excellent, although this highs get just a little muffled. We heard no distortion, even at high volumes, but the bass doesn't come through as strong as some might like.
Not offered in the Z4 sDrive35is is much in the way of driver assistance features. Forget blind-spot detection, adaptive cruise control, or even a back-up camera. But with the top down, visibility all around is excellent.
In sum
Although a very satisfying sport driver, the 2011 BMW Z4 sDrive35is pulls up a little short of the edge, trading in hard-line performance for creature comforts. The performance tech, from the direct-injection turbocharged engine to the adaptive suspension, is very advanced and seen in few other cars, and even fewer roadsters.
Our car came with a mostly bare cabin, but BMW makes an excellent array of electronics available. Very impressive for a roadster is the 8.8-inch LCD for the navigation system. The stock stereo system was very good, and we would expect quite a bit from the car's premium audio.
The car is also a looker, the hard top making a nice profile with the long-snouted roadster body. The retracting feature for the roof is very clever, but points off for the impact it has on the trunk space.
VIDEO REVIEW:
http://reviews.cnet.com/convertible/...html?tag=mncol