Classic roadster proportions give the Z4 a long hood and short decklid, shoulders over the wheel arches and tapers in three axes. Creases begin at the inner edge of the headlight housings, roll over the front fenders and lead back to bisect the door handles, while opposite lower sweeps started at the front bumper curve upward to the rear wheels.
In side view it looks like someone traced a French curve over each wheel, the forward one twice the length of the rear, and from the driver's perch the hood seems to rise from the windshield base before falling off forward. We think it 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 propeller logo is still here, but no longer serves to disguise the turn signal repeaters.
A variety of wheel sizes and finishes are offered, and while the Z4 is light and well-suspended enough that even 19-inch wheels can deliver decent ride quality, they might not work well on rough roads, and some wheel styles will require more cleaning effort.
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 its roadster precursor, the 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 30i, while the 35i and 35is have a single outlet on each side, a la Z8.
Exterior trim varies among the three models. The shape of the front of the car is the same for all models, illuminated with BMW's trademark corona daytime running lights (programmable). The sDrive30i has black vanes in its grille and a silver slash across the outer lower grilles, while the 35i has matte silver grille vanes and perimeter frames for the outer grilles, and the 35is has wider spacing of its grille vanes. 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 Z4 sDrive35is gets some other exterior changes. The M Sport package is standard, so it has a 10 mm lower ride height and different front and rear styling. The 35is modifies that styling with horizontal bars in the front outer air intakes and a body-color rear apron with a black lower diffuser. It also has oxide silver mirror caps, and a unique design for both the standard 18- and optional 19-inch wheels.
The 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, so exterior dimensions should not factor into purchase decisions.
The Z4 is built in Regensburg, Germany. In BMW fashion, many systems on the Z4 have been proven in other recent BMW models, including the higher-output engines, transmissions, and suspension design.
pound-feet of torque from 1400 to 5000 rpm; it is a different engine than the 30i and employs twin turbochargers. A 6-speed manual gearbox is standard and a 7-speed dual-clutch automated manual transmission (DCT) is optional ($1,575). Other mechanical upgrades include larger brakes and larger P255/40R17 rear tires. Cabin upgrades include standard leather upholstery, brushed aluminum trim or ash wood, and automatic dual-zone climate control. Options are similar to those above. Kansas leather upholstery on the dash, visors, and door sills ($1,350) is optional.
The Z4 sDrive35is features an engine with increased intake airflow and increased boost pressure to deliver even more power. Its maximum output is 335 horsepower at 5800 rpm and 332 pound-feet of torque from 1500 to 4500 rpm. In addition, its engine management system includes an electronically controlled overboost function which increases torque by another 37 pound-feet, for a temporary peak of 369 pound-feet for up to seven seconds.
The sDrive35is ($61,050) has the seven-speed dual-clutch transmission as sta
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 sDrive30i engine is a very light, modern, rev-happy unit that brings 255 horsepower at 6600 rpm and 220 pound-feet of torque at 2600 rpm; it has more than enough power for any road and delivers it in linear fashion, its output rising commensurate with revs. This package is EPA-rated at 18/28 mpg with both the manual and the automatic, numbers we easily met or exceeded when we drove one. This is a delightful engine, particularly with the manual.
The sDrive35i engine is a different animal altogether. It uses two very small turbochargers to boost maximum horsepower to 300 hp at just 5800 rpm. Even more noticeably, the turbos increase torque to 300 foot-pounds, on tap from just 1400 rpm through 5000. The extra muscle gets the sDrive35i (210 pounds heavier) to 60 mph a half-second quicker than the sDrive30i. That's 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 sDrive30i does. EPA numbers for the sDrive35i are 18/25 mpg with the manual transmission and 17/24 mpg with the DCT. With decent aerodynamic drag numbers, a relatively small frontal area and an efficient driveline, 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, plus an overboost mode allows for 14.6 pounds of boost for up to seven seconds. Those changes increase horsepower to 335 and up torque to 332 pound-feet. The overboost feature adds another 37 pound-feet of torque for a total of 369. 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 sDrive30i 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.
The sDrive30i automatic is a conventional 6-speed unit and goes about its business exactly as intended; it's not quite as quick as the manual, but it's easy to operate and more practical for commuting in heavy traffic.
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 charging downhill in 100-degree weather in an sDrive30i. 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.
Every Z4 is fun to drive, however. We found the sDrive30i with the Sport Package to be a sweet ride on a winding road where the lighter weight is felt. Compared to the sDrive35i, reactions and response seem more linear, and the whole effect is more pure sports car than racecar.
The sDrive35i, however, has considerably more power that keeps coming on strong. Speed merchants will prefer it.
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 standard Driving Dynamics Control. Driving Dynamics Control adjusts steering feel, throttle response, and the limits of the stability control system, and when paired with a sport package it adds electronic control of the shocks. It has 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. Still, it can't really 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.
Putting the top down doesn't change the behavior at all because it's the lightest such assembly in the industry thanks to aluminum panels. It changes front/rear balance by only 0.3 percent, and puts the weight of the top closer to the ground. You could argue lowering the top costs some rigidity as the triangulation between windshield, floor, and trunk is gone, but there is little-to-no cowl shake. 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.
The one thing you do have to get used to, depending on whether you're looking at the road or the hood, is what your brain might interpret as a momentary delay between when you turn the wheel and when the car rotates and changes direction. Since you sit so far from the front axle and very near the rear axle, steering inputs tend to send the hood off to one side before you feel the rear tires joining the party. It's a sensation the more driver-forward Audi TT doesn't exhibit, and it's much more muted in the softer Mercedes-Benz SLK. Nor does the mid-engine Porsche Boxster exhibit it.
Among the competitors, the SLK also offers a folding hardtop, while the TT and Boxster use folding cloth tops. Cloth tops are perhaps not as quiet and sealed as a hardtop, and not as easy to see out of, 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 even better driving precision, with power comparable to the sDrive35i and the driver's engagement of the sDrive30i, but the Boxster tends to cost more.
The 2011 BMW Z4 comes in three models, sDrive30i, sDrive35i, and sDrive 35is. In current BMW nomenclature, sDrive refers to rear-wheel drive. However, there are no xDrive (all-wheel-drive) Z4s and no M model has been announced.
The BMW Z4 sDrive30i ($46,000) comes with a 3.0-liter inline six-cylinder engine making 255 horsepower at 6600 rpm and 220 pound-feet of torque at 2600 rpm. It is mated to a 6-speed manual transmission; a 6-speed sport automatic with shift paddles is optional ($1,375). The Z4 comes standard with faux leather upholstery, manual climate control, interior air filter, cruise control, power retractable hardtop, heated power mirrors and rear window, power windows and locks, remote keyless entry, six-way manual bucket seats, tilt/telescoping leather-wrapped steering wheel with audio controls, rain-sensing wipers, AM/FM/CD stereo with HD radio, auxiliary input jack, trip computer, automatic adaptive bi-Xenon headlamps, and P225/45R17 run-flat tires on alloy wheels.
Options include brushed aluminum or ash wood trim ($500) and Kansas leather upholstery ($1,250), which includes the aluminum interior trim. The Ivory White Extended Leather package ($2,150) includes full Ivory Nappa White leather upholstery, sport seats, and Anthracite wood interior trim. The Premium package ($3900) includes dual-zone automatic climate control, leather upholstery, eight-way power seats with lumbar adjustment, memory for the driver's seat and mirrors, BMW Assist, Bluetooth wireless cell phone link, universal garage door opener, auto-dimming outside and rearview mirrors, and ambient interior lighting. The Sport package ($2,300) includes sports suspension with electronic shock absorber control, P225/40R18 front and P255/35R18 rear run-flat tires, light alloy wheels, increased top-speed limiter, and sport seats. A Cold Weather package ($1,000) includes heated seats, a heated steering wheel, a trunk passthrough and headlight washers.
New for 2011 is the M Sport package ($3,900) for the sDrive30i, which comes with an increased top speed limiter, sports seats, black headliner, body cladding, sports suspension with electronic shock absorber control, P225/40R18 front and P255/35R18 rear run-flat tires, and light alloy wheels. Also new for 2011 is Smartphone integration ($150). Other options consist of a navigation system ($2,150) with an 80-gigabyte hard drive, voice recognition, real-time traffic information and an iPod interface; front and rear park assist ($750); a Premium Sound package ($1,800) with 14 speakers, 650 watts, Sirius satellite radio and an iPod adapter; BMW Assist ($750); heated seats ($500); keyless access and starting ($500); satellite radio ($350); iPod adapter ($400); alarm ($400); and a trunk pass-through ($195).
The Z4 sDrive35i ($51,900) has a 3.0-liter inline-6 that delivers 300 horsepower at 5800 rpm and 300 pound-feet of torque from 1400 to 5000 rpm; it is a different engine than the 30i and employs twin turbochargers. A 6-speed manual gearbox is standard and a 7-speed dual-clutch automated manual transmission (DCT) is optional ($1,575). Other mechanical upgrades include larger brakes and larger P255/40R17 rear tires. Cabin upgrades include standard leather upholstery, brushed aluminum trim or ash wood, and automatic dual-zone climate control. Options are similar to those above. Kansas leather upholstery on the dash, visors, and door sills ($1,350) is optional.
The Z4 sDrive35is features an engine with increased intake airflow and increased boost pressure to deliver even more power. Its maximum output is 335 horsepower at 5800 rpm and 332 pound-feet of torque from 1500 to 4500 rpm. In addition, its engine management system includes an electronically controlled overboost function which increases torque by another 37 pound-feet, for a temporary peak of 369 pound-feet for up to seven seconds.
The sDrive35is ($61,050) has the seven-speed dual-clutch transmission as standard equipment, with the programming tailored to complement the nature of the car and engine. The sDrive35is also features some M Sport upgrades, including M Aerodynamics and adaptive M Suspension, which combines a ride-height reduction of 10 millimeters with electronically controlled shock absorbers to improve handling without compromising comfort. It also has special five-spoke 18-inch alloy wheels with P225/40R18 front and P255/35R18 rear tires. Options are similar to those above.
Safety features included on all Z4 models: dual frontal airbags, head/thorax side airbags in the seats, active knee protection, roll hoops, electronic stability, traction control, anti-lock brakes, and tire-pressure monitoring. Manual transmission models also have a hill-holder clutch to prevent the car from rolling backward when the clutch is engaged. The only option related to safety is the front and rear park assist.