BMW Z4 (E89)


Debut: 2009
Maker: BMW
Predecessor: Z4 E85



 Published on 20 May 2009 All rights reserved. 


New BMW roadster tries to be more SLK than Boxster...

BMW maybe renowned for producing sports saloons, but until now it has yet to master the know-how of sports cars. No matter Z1, Z3 or Z4, none came close to the level of Mazda MX-5 or Porsche Boxster. The outgoing Z4 especially attracted a lot of criticisms – weird looks, lifeless steering, harsh ride from run-flat tires and a chassis favouring understeer. If it were Audi, it would have sorted these problems one by one in the next generations until perfect. However, this is BMW, a company rarely responds to criticisms and always keeps doing what it thinks right. It refused to admit defeat, so it simply changed the nature of Z4, turning it into a luxury-biased coupe-cabriolet like Mercedes SLK. Can it save the game ?

The second generation Z4, codenamed E89, looks so familiar. There are detailed changes to its design, of course, but its roots cannot be more obvious. Like the old car, its proportion is so wrong, with a long long bonnet and a tiny tail. The small passenger compartment locates just in front of the rear axle, more like a 1936 Morgan than a modern sports car. The weird “Flame-surface” design theme continue to distort the body surfaces, creating tensions in the same way as a heavily bruised sardine tin. Chris Bangle or Adrian van Hooydonk makes no difference to the fate of this car.


“Flame-surface” design is about as stylish as a bruised sardine tin...

Like the exterior, the chassis is an evolution of the outgoing car. Its basic format of FR, MacPheson strut and multi-link suspensions and electrical power steering remain intact. Though being 148 mm longer, its wheelbase is virtually unchanged at 2496 mm, while the body is only 9 mm wider. Electronics-wise, it gets adaptive damping (if you opt for “Adaptive M Sport” suspension) and a switchable control system called “Dynamic Drive Control”, which offers 3 modes (Sport, Normal and Comfort) to alter damping stiffness, throttle response, steering effort, stability control threshold and transmission mapping.

However, the biggest change lies on the roof. In an attempt to lift showroom appeal, the BMW roadster follows Mercedes SLK to adopt a retractable metal roof, made of 2 aluminum panels and associated electrohydraulic mechanism. Press a button and the roof will rise from the boot in only 20 seconds. Now the Z4 provides all the noise insulation and chassis stiffness of a coupe, effectively eliminating the need to build Z4 Coupe, which was unfortunately the most lovely version in the past.

Nevertheless, the retractable roof has its problems, too. When being stored, it eats 130 liters of luggage space, leaving only 180 liters. But even more problematic is the additional weight it brings, which lifts the car some 100 kilograms above its equivalent predecessor. You know, more weight leads to slower performance and poorer handling. We shall review its dynamic aspect later on.


Retractable roof kills the lovely Z4 Coupe...

Apart from the roof, the cabin is another area of vast improvement. While the basic architecture and the snug feel remain, the redesigned dashboard and console, taking inspiration from the late Z9 (nearly forget that car), looks more stylish. Materials are more expensive. New i-Drive becomes much more intuitive. As before, you sit low in the cockpit, near the rear axle and view forward across the long bonnet.

Annoyingly, BMW names the versions of new Z4 as sDrive23i, sDrive30i and sDrive35i, in which "sDrive" represents rear-wheel drive (versus "xDrive" for 4WD) and the number refers to its confusing engine performance index. The sDrive23i is powered by the existing 2.5-liter Valvetronic magnesium crankcase straight-6 with 204 horsepower. Performance is 148 mph top speed and 0-60 mph takes 6.3 seconds with 6-speed manual gearbox. Alternatively you can opt for a 6-speed Steptronic automatic.

sDrive30i employs the 3.0-liter version of the Valvetronic magnesium crankcase straight-6. Confusingly, its output drops back to 258 horsepower from the previous 265 hp. It will top a regulated 155 mph and sprint from 0-60 mph in 5.6 seconds, which is slower than the old car due to the extra weight. Transmissions are the same as the base engine.

 


Dashboard and console takes inspiration from the late Z9...

sDrive35i is the new range topper. It uses the now familiar twin-turbo 3.0-liter direct-injection straight-6 with 306 horsepower and 295 lb-ft of torque. Mate with manual box it delivers 0-60 mph in 5.1 seconds and 30 mpg combined consumption. Like M3 and 335i coupe, it offers the new 7-speed DCT double-clutch gearbox as option, which reduces 0-60 mph by 0.1 second. All six-cylinder engines are now part of the “Efficient Dynamics” package, which include brake energy regeneration, on-demand coolant / oil pumps, electrical power steering and low rolling resistance tires to reduce fuel consumption and emission.

On the Road

The change of personality is instantly obvious on road. For the first time ever, the Z4 rides supplely on anything but the roughest. Its damping over primary ripples is especially improved, making it much less painful to travel on country roads. The stiffer chassis does not shake or squeak under cornering load, adding to the refined feel. If you opt for the DCT double-clutch gearbox, you will be amazed by its seamless gearshift, too.

You can’t argue that BMW has the best six-cylinder engines in the world – smooth, refined and willing. They help making the new Z4 a good companion for motorway cruising.

A 3-Series saloon is probably more fun to drive...

However, when the road get twistier, you will find its chassis has lost the honesty of the old car. Its extra weight and refinement seem to add a thin layer of isolation between the man and machine. For example, prod the throttle, the engine does not respond as quickly as you would expect in a lightweight roadster. Push it into corner, it rolls more than a sports car should, while its nose runs wide more easily than you expect - understeer is still the family name of Z4. The electrical power steering is once again too slow (2.7 turns from lock to lock) and too numb. The long distance between the driver and the front wheels adds to the sense of isolation.

In fact, a 3-Series saloon is probably more fun to drive than the Z4, which hurts.

BMW has confirmed that there won’t be a M version to follow. It argued that a Z4 sDrive35i with DCT transmission and Adaptive M suspension is already capable enough to replace the old Z4 M. Price-wise, the £40,000 combination really leaves no space for the M car. Fun-wise, however, it will never fulfill that vacancy.
Verdict: 
 Published on 10 Mar 2010 All rights reserved. 
Z4 sDrive35is

With more power and sharper suspension tuning, is this finally the BMW sports car we have been expecting ?

We had a lot of complaints on the second generation Z4: 1) Its styling suits only acquired taste; 2) It got heavier due to the bulky roof mechanism, dampening performance; 3) Its chassis dynamics became civilized, losing the raw excitement of the original car. The first problem is not going to be solved until the next generation is introduced, but the second and third problem may be addressed by the new range topper, sDrive35is.

As implied by its name, sDrive35is is not a big departure from the existing sDrive35i. Its heart is still that N54 twin-turbo 3.0-liter straight-six, but higher turbo boost lifts its output to 340hp and 332 lb-ft, compared with the original 306hp and 295 lb-ft. Moreover, it enables a momentary overboost to 369 lb-ft. All these are done without altering the internals of the engine, proving how tunable the N54 is. To improve performance further, 7-speed twin-clutch DCT gearbox comes standard on the sDrive35is. This combination results in a much more satisfying performance, i.e. 0-60 mph takes only 4.7 seconds, although top speed is regulated at 155 mph as usual. This car is every bit as fast as the outgoing Z4 M Roadster, though its power delivery and sound are no where as exciting. Like the regular N54, its power delivery is smooth and free of turbo lag. You get maximum thrust from just 1500 rpm, and maximum power is reached at 5900 rpm, so it never tempts you to access the upper end of rev range. The DCT box is also less engaging to use than the M-car's 6-speed manual. However, compare with lesser Z4s its performance edge is still a welcomed improvement.

The sDrive35is gets a slightly more aggressive aero kits (which will be offered to lesser models as option) and adaptive M sport suspensions. The latter includes stiffer springs and adaptive dampers, thicker anti-roll bars, 18-inch low profile tires and 10 mm lower ride height. These changes successfully sharpens its handling, bringing tighter body control and sharper turn-in without damaging ride quality much. It is a well-judged compromise. The handling becomes more neutral. With stability control disabled you can access to a progressive power slide.

Nevertheless, the sDrive35is is hard to recommend because its price matches that of Porsche Boxster S. Yes, it has a decisive performance edge over the Porsche, but it is no where as engaging to drive, let alone looks.
Verdict:

 Published on 14 Oct 2011 All rights reserved. 
Z4 sDrive28i with N20 engine


For decades, BMW's straight-sixes have been one of the best engines in the automotive world. However, under the pressure for reducing emission and consumption, its days are numbered. From now on, the naturally aspirated version of the straight-six, no matter in 2.5-liter or 3-liter form, will be replaced with a 2-liter turbocharged four-cylinder engine codenamed "N20". This will begin from the Z4, then 5-series, 3-series and eventually all other models. Only the turbocharged version of the straight-six (on the "35" models) will escape from the axe, because it is being used as a downsized substitution to V8.

On paper, the N20 loses little to the straight-six. Thanks to the incorporation of Double-Vanos, Valvetronic, direct injection and a twin-scroll turbocharger, it produces a respectable 245 horsepower, trailing the standard tuned 3-liter straight-six by only 13 horses. On the other hand, its torque delivery overwhelms the latter, with 258 lbft delivered from just 1250 rpm against 221 lbft at 2600 rpm. This mean in the real world the smaller engine actually feels punchier than the old one. Moreover, the loss of two cylinders and the inclusion of automatic stop-start achieve 20 percent lower fuel consumption, raising the mpg figure of Z4 from 33.2 to 41.5 mpg. The corresponding carbon emission is lowered from 199 to 159 grams per km.



However, is it really by all means better than the traditional straight-six? Of course not. While it is certainly more efficient, it is not as inspiring to drive. No matter how great an inline-four engine is tuned, it still fails to produce a melodious symphony that the old straight-six plays. The same goes for smoothness and the eagerness to rev. Although it is said to be redlined at 7000 rpm, it is reluctant to do so. As the output peaks at only 5000 rpm, higher rev brings little reward but more protest in noise and refinement. In other words, it does not encourage you to use more of it. A more laid-back style is preferred. Doesn't it sound very un-BMW?

Theoretically, the four-banger's 10 kg lighter weight and shorter length could improve weight distribution thus handling. In the real world, however, no obvious change can be felt on the Z4 sDrive28i. This is still a dull car to drive. The switch to N20 engine only continues BMW's trend of going ordinary. In fact, from the recent 5-series and 1-series we can also see BMW is losing focus on driving fun. Perhaps it's time to stop and rethink whether emission is top priority to the brand.
Verdict:
Specifications





Year
Layout
Chassis
Body
Length / width / height
Wheelbase
Engine
Capacity
Valve gears
Induction
Other engine features
Max power
Max torque
Transmission

Suspension layout

Suspension features
Tires

Kerb weight
Top speed
0-60 mph (sec)

0-100 mph (sec)

Z4 sDrive23i
2009
Front-engined, RWD
Steel monocoque
Mainly steel
4239 / 1790 / 1291 mm
2496 mm
Inline-6
2497 cc
DOHC 24 valves, DVVT, VVL
-
-
204 hp / 6400 rpm
184 lbft / 2750 rpm
6-speed manual

F: strut
R: multi-link
-
225/45WR17

1405 kg
148 mph (c)
6.3 (c)

-

Z4 sDrive30i
2009
Front-engined, RWD
Steel monocoque
Mainly steel
4239 / 1790 / 1291 mm
2496 mm
Inline-6
2996 cc
DOHC 24 valves, DVVT, VVL
-
-
258 hp / 6600 rpm
221 lbft / 2600 rpm
6-speed manual

F: strut
R: multi-link
-
225/45WR17

1415 kg
155 mph (limited)
5.5 (c)

-

Z4 sDrive35i
2009
Front-engined, RWD
Steel monocoque
Mainly steel
4239 / 1790 / 1291 mm
2496 mm
Inline-6
2979 cc
DOHC 24 valves, DVVT
Twin-turbo
DI
306 hp / 5800 rpm
295 lbft / 1300-5000 rpm
6-speed manual or
7-speed twin-clutch (DCT)
F: strut
R: multi-link
Adaptive damping
F: 225/45WR17
R: 255/40WR17
1505 kg (DCT: 1525 kg)
155 mph (limited)
5.0 (c) / 4.8* (6M)
4.9 (c) / 4.8** (DCT)
11.7* (6M)
11.7** (DCT)




Performance tested by: *C&D, **R&T





Year
Layout
Chassis
Body
Length / width / height
Wheelbase
Engine
Capacity
Valve gears
Induction
Other engine features
Max power
Max torque
Transmission
Suspension layout

Suspension features
Tires

Kerb weight
Top speed
0-60 mph (sec)
0-100 mph (sec)
Z4 sDrive35is
2010
Front-engined, RWD
Steel monocoque
Mainly steel
4244 / 1790 / 1284 mm
2496 mm
Inline-6
2979 cc
DOHC 24 valves, DVVT
Twin-turbo
DI
340 hp / 5900 rpm
332 lbft / 1500-4500 rpm
7-speed twin-clutch
F: strut
R: multi-link
Adaptive damping
F: 225/35YR19
R: 255/30YR19
1525 kg
155 mph (limited)
4.7 (c) / 4.8*
11.3*
Z4 sDrive28i (N20)
2011
Front-engined, RWD
Steel monocoque
Mainly steel
4239 / 1790 / 1291 mm
2496 mm
Inline-4
1997 cc
DOHC 16 valves, DVVT, VVL
Turbo
DI
245 hp / 5000-6500 rpm
258 lbft / 1250-4800 rpm
6-speed manual
F: strut
R: multi-link
-
225/45WR17

1400 kg
155 mph (limited)
5.4 (c)
-




























Performance tested by: *AMS





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