BMW Z4 sDrive35i 2009 Review - International

BMW Z4 sDrive 35i

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OVERVIEW
The old Z4 was much loved by enthusiasts, but didn't sell with the consistency BMW was looking for. Typically, its sales spiked on the back of significant upgrades such as new/higher hp engines or when a new rival brought new customers into the two-seat roadster market for a look-see.

But, as a pure-bred, hard-core sporting drive, the old Z4 sat nicely between like-minded convertibles like the Nissan 350Z and Audi TT and the faster, pure-bred Porsche Boxster S. It was the hardest edge you could buy on any BMW without an M badge and it was good enough to hold its own in any company on almost any road.

That said it was a long way from being perfect, and that's where the new Z4 comes in. The original had ride and it had quality, but those in the know were wary of combining the two terms in one sentence. The run-flat tyres combined with shortened suspension travel and stiff springs to make the Z4's ride an acquired taste if you regularly drove over broken or potholed roads.

Its interior was also small and there was nowhere to put a mobile phone, a set of keys, a wallet or almost anything else -- so there was some obvious work to be done there.
Other than that (and, for the purists, more steering feel), the formula seemed pretty settled with a long-nose, six-cylinder petrol engines, short tail and a low seating position.

On paper, the biggest changes wrought on the new generation are the adoption of the folding metal hardtop roof and the shift of the Z4's production base from Spartanburg in the US to Regensberg in Germany. With the US plant now solely dedicated to the X3, X5, X6 and the upcoming X1, the Z4 is now built at home alongside the 1 and 3-series.

PRICES AND EQUIPMENT
While BMW has yet to announce its Australian pricing for the Z4's three-strong model range, anybody expecting to walk straight out of an old Z4 into a new one will be in for a rude shock.

The Z4 has packed on the beef over the off-season and not just in picking up the folding aluminium roof system. Where the old Z4 was minimalist, the new one is now trying to be all things to all people -- and that means it has a lot more stuff and has gone from a mid-range roadster on price to being a properly expensive machine in the Porsche Boxster region.

At least BMW has taken advantage of the extra size of the new Z4 to fill it with more goodies. It has the latest generation of iDrive and the top equipment level has (in Europe at least) internet connectivity so you can plan a tour, complete with way points, on Google maps and send the route wirelessly into the onboard navigator's brain.

It scores the iDrive controller upgrade from the new 7-Series, which makes the entire in-car electronic systems easier to use than before and takes up less space. The biggest step forward is, ironically, a step backwards with the introduction of a "back" button for those times when you stumble onto the wrong page.

The 8.8-inch screen is much larger, too, with high-definition graphics and an internal hard drive that contains all the mapping information for the GPS and can still take a few thousand of your favourite songs.

The basic version has a CD player that can also read in MP3 format, but you can option up the Z4 to have 14 speakers with 650 Watts of power. Not bad for a two-seater. While an Aux-in port is standard, a USB interface is optional and you can put a CD/DVD changer in the glovebox.

The seats are leather, of course, and the new hard roof is lined in Alcantara.

MECHANICAL
While three six-cylinder petrol engines lurk within the Z4's long, now-fluted bonnet, the BMW folks refused us access at launch time to anything but the strongest, most-powerful 3.5-litre twin-turbo engine.

A much-praised engine, it first saw service in the 3-Series as the 335i and quickly become noted for its big-diesel-esque strength in the mid-range combined with terrific responsiveness to the accelerator pedal.

Based on the sums, it shouldn't struggle to deal with the Z4's body and it doesn't. The flat, broad torque curve quickly hits 400Nm and seems to stay on top of it forever. To achieve this, BMW gave its 3.0-litre in-line six a pair of light-pressure turbochargers. They are both on the small side, and they're designed to boost the low-rev urgency by spinning up quickly and leaping to attention the instant the driver asks them to. (Larger, single turbos can be on the slow side to deliver their best work and can be slow to respond to changes in the throttle inputs.)

BMW has connected this up to a seven-speed, double-clutch gearbox (a la the 3 Series Coupe, not M3), which works superbly. Mostly, anyway.

While the main structural points in the chassis are steel (with grades varying from the traditional variety to a boron alloy that is eight times stiffer), BMW has lavished aluminium at either end in a vain attempt to keep the Z4's weight in check.

The front axle has had a major overhaul, with a double-joint tiebar system made almost exclusively from aluminium and combining with traditional front struts. The rear suspension is compact, with longitudinal arms attaching to the body and track control arms attaching to the axle's subframe.

The Z4 receives the second generation of electronic power steering -- the first generation provoked some of the most strident common complaints in the old car. It saves fuel, because it only runs the power steering's electric motor when it needs to, but it robs the driver of some direct feedback.

It's all helped by very sophisticated stability software, and the car rides on 17-inch run-flat tyres as standard.

While it has no mechanical limited-slip differential, BMW uses the Dynamic Stability Control's software to brake the inside wheel when it's spinning, sending the drive to the outside to give it better traction. All of the test cars also ran on the optional Adaptive M suspension, which drops the car 10mm and gives it electronically controlled shock absorbers.

In yet another example of BMWs' bewildering array of acronyms, this suspension system upgrade links up with Dynamic Drive Control (DDC) to give the driver Normal, Sport and Sport+ chassis set up options. As per the one-touch button in the 7 Series, these are software packages that affect the throttle response, the steering response, the shock absorber setup, the gearshift speeds and the stability control thresholds.

PACKAGING
The new Z's a slightly larger car than its predecessor, but it had to be to meet BMW's design aims for it. There's a scant 1mm difference in wheelbase between the generations, but at 4239mm long, 1790mm wide and 1291mm high it's longer (148mm), wider (9mm) and lower (8mm) than the current generation. (By comparison the latest Boxster is 90mm longer overall and 11mm wider but almost the same height)

The end result, however delivers noticeably more headroom, shoulder room, elbow room and bigger door openings.

Push the roof button and, 24 seconds later, you'll be in full roadster mode. (BMW claims 20 seconds, but on four timed runs, we couldn't do it faster than 24.)

The boot lifts its leading edge and four windows slide down into the bodywork before the roof snaps itself in half to walk down into the boot. Yes, four windows. BMW needed them, even though it's only a two-seat roadster, to maintain the shape its designers wanted.
There's an optional remote system, running off the key, to open and close it from outside the vehicle (just the thing for café crawlers) called Comfort Access, and when you open its boot, the folded roof lifts up to an interim position to allow easier access to your luggage.

The boot has 310 litres of space and, impressively, it still gives 180 litres even with the roof folded into it.

Where the old Z4 offered seats and not much more, the new one has ten litres of oddments storage inside the cabin, plus the folding compartments in each of the doors.
There is a tray in the centre console, another storage spot behind the gearshift, 1.6 litres of space inside the armrest and more space in the dashboard.

There's also a very handy spot to put bits and pieces running across the back of the cabin. Plus the optional Storage Package (highly recommended) delivers cupholders, cargo nets and a storage box.

SAFETY
While it's not the car to run the kids to school, the Z4 has had a lot of work done to maintain its safety record.

The body structure is incredibly stiff, there are head/thorax airbags at the front and at the side of the seats, it features new seat-belt-tightening technology, roll bars behind the seats and tremendously stiff windscreen pillars.

The full compliment of BMW's active safety systems is also standard. More on this when the car is launched locally next month.

COMPETITORS
Where the old car straddled the gap between the 350Z and Boxster roadsters, the new one has moved up market closer in price to the Porsche -- at least in terms of European pricing. Expect as much when it arrives Down Under.

That said, the Boxster isn't the only Stuttgart machine to be targeted. Mercedes-Benz's SLK is an obvious rival, as are Audi's larger-engined TTs.

BMW also thinks it has the interior and sophistication to go after more expensive machines, such as Jaguar's convertible XK.

With the roof up, the Z4 is quiet, calm and feels just like a fast, strong coupe in a slightly Grand Tourer sort of way. There is no wind noise to speak of, even up to 150km/h, and the fit and finish of the roof and its sealing is impressive.

But going topless defines a roadster, and the Z4 always did this with aplomb. It still does (though why it needs the weight and cost of wet rear glass is beyond me). The wind deflector works beautifully with the side windows to keep conversation easy, even at highway speeds and it feels right, stiff and strong.

For all that, though, the new Z4 is dominated by the character of its engine and by a chassis that overwhelms with competence, rather than any glittering brilliance.

With the engine, it's the Z4's torque, rather than the 225kW of power, that defines the top-spec Z4. That's completely at odds with its predecessor, which was identified by its sweet-spinning, naturally aspirated inline six that was torquey enough, but whose performance delivery rose to a crescendo as the revs climbed. It's another indication that this Z4 isn't aimed exactly at the old car's customers.

The shifts are seamless and fast and it has a Sport mode for even faster shifting (which has the bonuses of a wonderful braaaping sound on each upshift and a perfect heel-toe blip on each downshift). Strange, then, that BMW tries to downplay the future of double-clutch gearboxes within its range; isolating them to harder-edged cars like the Z4 and insisting, instead, that its future lies with advances in automatic transmissions.

The biggest issue is the shifting arrangements when you're in manual mode. You can use the gear lever for each shift by pushing it across into Manual mode and it works in the biomechanically correct way (forward as a downshift, back as an upshift). Try using the steering-wheel-mounted buttons, though, and your cornering can deteriorate as you try to second guess and then rethink what you're supposed to be doing with them.

BMW had a simple left-is-down, right-is-up system with its paddles in the M3 and M5, so why they tried to rewrite the rules with this less-natural system is anybody's guess. On the Z4, pull on either the left or the right paddle and you go to a taller gear, while lifting your thumb up and above the steering wheel spokes to push a button forward will change down.

The range will come with a six-speed manual in the smaller-engined models, but we didn't get to sample it on the launch.

What we did sample was the acceleration of the twin-turbo six and it's impressively fast, punching to 100km/h in 5.1 seconds and sprinting to a 250km/h (limited) top speed. That's considerably quicker than the old car could manage, but it didn't have two turbos feeding the engine, so it's not a valid comparison.

Instead, the old car should realistically face off against the new Z4 sDrive30i. It has largely the same engine as the old 3.0-litre in-line six, but it's been shorn of five of the old version's 195kW in an effort to drop its CO2 down from 204g/km to 199. It's also 0.1 seconds slower to 100km/h, which isn't a bad effort, given that the car is 105kg heavier with less power.

The twin-turbo is heavier again -- 175kg more than the old car. And it's added mass that no amount of electronic trickery can hide, much less turn into driving entertainment.

While it probably helps to improve the ride quality that was another Z4 bugbear, the brakes, suspension, engine, gearbox, tyres and steering all have to manage the extra passenger-and-a-half of mass. They do, but in the fog of it all, they drop Sheer Driving Pleasure from the armoury.

Instead, you find that pushing the Z4 through corners leaves you impressed with the engineering and the competence, but you never quite find the fun in it. It doesn't help that the steering feel is quite odd, requiring a hefty push to turn in Sport or Sport+ modes and, with very little self-centreing, another hefty push back the other way to straighten the car up again out the other side.

It also demands 2.7 turns lock-to-lock, which seems a little slow for a sportscar, and doesn't give you a lot of feel under any circumstances. And, invariably, when it runs out of grip, it runs out of grip at the front end.

But there's grip there, and lots of it. The Z4 has neck-bending lateral grip and tremendously strong brakes to back up its straight-line zot, and most of the electronics work seamlessly and unobtrusively. Every now and again a sharp bend will catch the electronic diff snoozing and light up the traction control button, but it's mostly flawless.

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