Unlike any other type of car, cruising in a roadster captures both the best and worst about driving. Top down, the wind rushes through your hair, every passing scent fills your nostrils (whether pleasant or not) and it's easy to feel at one with the road. But when it's time to put the top up, the fun usually ends.
Thanks to its retractable hardtop, the BMW Z4 offers the freedom of a convertible with the convenience of a coupe: more security, superior chassis rigidity, more rearward visibility and less susceptibility to pesky weather. While Porsche focuses more on performance and Mercedes seems to emphasize luxury and comfort, the BMW Z4 strikes a happy medium.
The 2012 BMW Z4 offers a choice of turbocharged engines: a 240-hp 2.0-liter turbocharged inline-4 in the new sDrive28i, a 300-hp 3.0-liter turbocharged inline-6 in the sDrive35i, and a 335-horsepower 3.0-liter turbocharged inline-6 in the sDrive35is.
New for 2012 is the Z4 sDrive28i, which replaces the outgoing sDrive30i. The 2012 BMW Z4 comes standard with more features than before (although the base price has also increased), including Bluetooth, a USB port and floor mats. The current-generation Z4 sDrive35i was launched as a 2009 model. The Z4 sDrive35is was introduced as a 2011 model.
The new 2012 BMW Z4 sDrive28i is the base model and the first to use BMW's all-new N20 engine, a 2.0-liter twin-powered turbo four-cylinder that makes 240 horsepower, slightly less than the venerated, naturally aspirated inline-6 it replaces, but with more power available at lower revs, along with 30 percent more torque. As they say, horsepower sells cars, while torque wins races.
Four-cylinders have never been a staple in the BMW lineup; earlier use was limited to a few models with less-than-stellar performance, and Munich's engineers admit it wasn't an easy decision to return to smaller powerplants. But with increased global pressure to reduce emissions, all automakers are faced with the challenge of increasing efficiency while maintaining performance. Several technologies in BMW's new engine enable the Z4 to keep its sporty dynamics while achieving what BMW says will be a 20 percent improvement in fuel economy. For one, the crankcase is about 22 pounds lighter. High-pressure direct injection as well as electronic variable valve timing uses fuel more efficiently than older systems. And the turbocharger, which consists of one turbine directed into two chambers (hence BMW's TwinPower nomenclature), uses engine exhaust to generate an extra boost of power.
Slightly quicker is the Z4 sDrive35i. EPA numbers for the sDrive35i are 18/25 mpg with the manual transmission and 17/24 mpg with the DCT. The sDrive35is delivers even better performance with the same fuel economy.
We found the Z4 offers the nimble, responsive driving character one would expect from BMW. The performance and feel of balanced precision is there in every Z4. Models with the manual transmission and devoid of many of the techno-gadgets including iDrive will make for the most sporty, free-feeling roadster, while heavier, highly optioned Z4s feel more like grand touring machines than sports cars. For car club track days, the high-performance sDrive35is with the dual-clutch gearbox might be the hot setup.
We think this roadster is best suited to someone who values luxury as much as performance. The closest competitors to the 2012 BMW Z4 include the luxe Mercedes-Benz SLK roadster and the Audi TT. For those who want an unadulterated roadster that gives the true feeling of the open road, the Porsche Boxster might be a better choice. But in general, the BMW Z4 does an admirable job combining fun, comfort and style.
Classic roadster proportions give the Z4 a long hood and short decklid, shoulders over the wheel arches and tapers in three axes. While the Z4 is close to the ground, it is not prone to scraping at every speed bump or mild driveway entrance because the front overhang is shorter than that of many other sports cars. Short overhangs are better for handling.
The BMW Z4 is longer than the Audi TT and Mercedes-Benz SLK, and it's shorter than the Porsche Boxster, though the difference among them is only a few inches. In height and width, they are much closer. We think the BMW looks better with the top down, but it's still relatively sleek top-up, and its closed profile is similar to that of the Mercedes SLR. Gills behind the front wheels carry the substantial badges, and the side signal repeaters are located behind opaque panels in the gills; the BMW roundel is still here, but no longer serves to disguise the turn signal repeaters.
From dead-on at either end with the top down, the Z4 has strong resemblance to a scaled-down version of the 6 Series and the short-lived, Fisker-designed Z8. Sections of the taillights look like horizontal light tubes and appear to ramp up like theater lights when the lights are switched on. Adaptive brake lights deliver more red light when you hit the brake pedal hard than when merely slowing mildly. The center brake light is midway between the rear window and the tail on the trunk lid where it will not interfere with rear vision but will be covered up by an inch of snow. A single side twin-exhaust outlet signals a 28i, while the 35i and 35is have a single outlet on each side.
The Z4 cabin is immediately familiar to any BMW owner, with many of the Munich builder's hallmarks: Simple white-on-black analog instrumentation, sweeping driver-centric lines, functional controls, and a high level of fit and finish (apart from the molding seams on the map pockets). The controls and optional navigation screen are easy to read, even in direct sunlight.
There is plenty of space for two people in the Z4, the head and legroom being about what you find in a midsize SUV. Though instead of sitting upright, driver and passenger site low with legs stretched out in front. Standard manual seats and tilt/telescoping steering column provide enough adjustment to suit many driver sizes; slender types will appreciate the side bolsters on the seats and larger bodies will be framed as much by the door and console. While they may not look like thick armchairs, the seats offer excellent support over multi-hour drives; the sport seats are a bit more confining for those of wider girths yet superb for a spirited drive. The driver's footwell is large enough for size 13 shoes to comfortably operate three well-positioned pedals and there's a good dead pedal on which to rest or brace your left foot.
Cubby storage has long been the bane of roadsters, but the Z4 fixes this with door pockets that tilt out for access (they also make excellent coin catchers for the change flying out your pants pocket at the first hard bend). A bin ahead of the shifter is good for a mobile phone or pair of sunglasses. Cars without the navigation system get a cubby atop the dash. The armrest lid conceals two cupholders, which can get in the way when shifting on cars equipped with the manual transmission. A third cupholder clips in to the side of the center console on the passenger side, but we find it awkwardly placed and annoying to attach and take off.
The multifunction steering wheel is communicative and feels substantial in-hand. The M Sport wheel is even thicker and easy to maneuver. Ahead of the wheel are a large speedometer and tachometer, with smaller fuel and oil temperature gauges (more useful than coolant temperature) in the bottom. Digital displays in the center list outside temperature, mileage, trip data, and, on automatics, gear indication.
Outward visibility is good, even with the top up. Taller drivers, however, might have to look around the inside mirror on up-and-down winding mountain roads. The three-quarter view right behind the seats is mostly unobstructed because the folding top design includes two small windows.
Climate control responds immediately to an adjustment in temperature. Other controls are easy to reach and well thought out. For example, there is no need to hold the trip odo button to reset it, and some controls are designed as multifunctional with one result from a quick tap and another by depressing and holding. The parking brake is electrically operated by a switch behind the manual shifter, and it does get hot in sunshine, even when on the road.
The top opens and closes in 20 seconds without any fear it will bump you on the head. Once up, the Z4 feels just like a coupe in terms of noise abatement. Raising all four windows (use the master switch on the driver's door) allows conversation at 75 mph with the top down, and most window-down wind noise comes from the area around the seatbelts. There is no wind-blocker panel for between the headrests, as specified in early option sheets, though we have seen photos and it may become available through your dealer.
Cargo room is about average for the class at 8 cubic feet with the top up. The pass-through slot is helpful with storing longer items.
The BMW Z4 is clearly aimed at those who enjoy driving. The retractable hardtop and added features have nudged it a bit closer to grand touring car than sports car. The inline six-cylinder engines rev smoothly to redline.
The shift lever on models equipped with the automatic transmission and the DCT is a bit tricky to figure out and takes a while to get used to. Neutral is the default position and Park is a pushbutton; push the lever forward for Reverse and backward for Drive.
The new four-cylinder engine on our sDrive28i was snappy and able. We noticed the extra torque when passing slow-moving trailers on a two-lane highway, although we did find ourselves wishing for the extra power of the higher-end models when making passes through hilly terrain. The 8-speed manual transmission gave us the gear we needed, and when in Sport mode, didn't give us any unwanted upshifts. But, given the choice, we'd prefer the manual gearbox.
The more powerful sDrive35i gets to 60 mph a tad quicker than the sDrive28i, with plenty of power for street and track alike. It will wind to 7000 rpm but there's really no point with that abundance of torque, and while it's a superb engine it doesn't offer the delightful rev-happy feel the sDrive28i does. EPA numbers for the sDrive35i are 18/25 mpg with the manual transmission and 17/24 mpg with the DCT. We managed almost 24 mpg in a manual-transmission model over some amusing roads and 38 mpg at 72 mph on an 80-mile leg from 4,000 feet elevation down to 700.
The sDrive35is model has a more powerful version of the twin-turbo engine. Turbo boost increases from the sDrive35i's 8.7 psi to 11.6 psi in the sDrive35is. Those changes increase horsepower to 335 and up torque to 332 pound-feet. An overboost mode allows for 14.6 pounds of boost for up to seven seconds. The overboost feature adds another 37 pound-feet of torque for a total of 369 lb.-ft. Aggressive exhaust tuning gives the sDrive35is a great burble. The extra boost cuts 0.3 off the 0-60 mph time, which is an impressive 4.7 seconds. It comes only with the DCT. Fuel economy is the same as in the sDrive35i at 17/24 mpg.
The 6-speed manual transmissions for the sDrive28i and sDrive35i offer soft, progressive clutch take-up for smooth starts whether crawling in traffic or weekend autocrossing. Shift action is light, short and semi-notchy, rather like there's a rubber-edged metal gate hiding under the shift boot. Shifts are quick, clean, and error-free.
BMW's 7-speed DCT dual-clutch automated manual transmission comes standard in the sDrive35is and is optional for the sDrive35i. Also used in the M3, this transmission has clutches, but there is no clutch pedal. Put it in Drive and step on the gas. Around town you will feel like it has a momentary delay between when you press the accelerator from a stop and when the car starts moving.
The DCT can shift faster than a manual transmission, emitting brief burps from the exhaust pipes as it rips through the gears. It's also smart, dropping gears automatically (rev-matching the downshifts) when you brake hard for a corner, but it will shy away from gear changes mid-corner so it doesn't upset the balance of the car. There is a launch control mode for ultimate acceleration, but make sure to read the owner's manual cautions before you take the steps and disappear in a wisp of tire haze.
Brake performance and feel is good across the range. We had no brake issues during a day at the track in the sDrive35is. Nor did we experience fade when tossing the sDrive28i from corner to corner in near-100-degree weather. Since they have more power and weight, the turbocharged sDrive35i and sDrive35is get substantially larger brakes, and that may be a deciding factor for drivers intending to take their Z4 to track events. These models also have wider rear wheels and tires to cope with the added weight and power.
For the ultimate performance, though, the sDrive35is is the clear choice. It delivers performance levels exceeded by only the most powerful, and expensive supercars. We had the opportunity to drive it on a racetrack and there it felt right at home, hunkering down through corners, accelerating willingly, braking with power, and staying flat and balanced. For those hoping for a Z4 M, this is as close as it gets.
We found the Z4 rides commendably well, even on the standard run-flat tires (no spare) and optional Sport Package. Credit the rigid structure, BMW's magical suspension tuning, and the technology involved in the Driving Dynamics Control, which adjusts steering feel, throttle response, and the limits of the stability control system. A sport package adds electronic control of the shocks with Normal, Sport, and Sport-Plus settings. The Normal mode is the most relaxed, and it's the choice for the highway or around-town cruising. Sport and Sport-Plus sharpen the responses and firm up the ride. These modes are meant for more spirited driving. Choose the mode that fits your preferences, mood and situation.
Steering is electromechanical but you'd never tell by how well it communicates what the front tires are doing. Unlike many sports cars, in which it seems that heavy steering was a design requirement, the Z4 steering is light around town, weights up nicely with cornering force and reminds us somewhat of the Honda S2000. The sDrive35is model is a bit quicker and sportier. It can't match the surgical detail of the Porsche Boxster, but nothing at this price, short of a Lotus, does.
With a low center of gravity and near-perfect weight distribution with occupants, the Z4's handling is exemplary. You'd need something considerably lighter, more stiffly sprung, and equipped with fatter or stickier tires to make notably faster progress. The Z4 is not only nicely balanced and goes where you point it, it does so with little drama and it's relatively easy to find where its limits are.
Every Z4 model is fun to drive in its own way. And while the hard top does offer added sound insulation over a traditional soft top, it was still noisy. Both road, tire and wind noise penetrated the cabin at highway speeds. But to some extent that's to be expected in this type of little car.
Putting the top down doesn't change the Z4's behavior thanks to its lightweight aluminum panels. We found that the inside mirror and only the inside mirror vibrated a bit on poor road surfaces, a sign that body rigidity characteristics don't change much top up or top down.
Among the competitors, the Mercedes-Benz SLK also offers a folding hardtop, while the Audi TT and Porsche Boxster use folding cloth tops. The latter are perhaps not as quiet and sealed as a hardtop, but trunk space doesn't suffer as much when motoring top-down. The Audi TTS has the foul-weather bonus of all-wheel drive and a nicely finished cabin, but not the same balance and precision finesse as the Z4. The Mercedes offers many similar amenities but is less a driver's car and more a small version of the SL luxury convertible. The Boxster has better driving precision, with power comparable to the sDrive35i and the driver's engagement of the sDrive28i, but the BMW isn't as painful on the wallet.
The BMW Z4 reminds us of a more intimate and engaging version of the 6 Series Convertible. The folding hardtop offers the best of coupe and roadster forms with few of the drawbacks of either. The Z4 sDrive35is carries a hefty premium, but it is the most powerful and the best performer. We recommend the base Z4 sDrive28i with its lively engine, especially with the manual gearbox.
NewCarTestDrive.com correspondent Laura Burstein reported from Carmel, California, with G.R. Whale reporting from Los Angeles, and Kirk Bell in New Jersey.