BMW Z4 Coupe 2006 Review

BMW Z4 Coupe

Not so much
>> Busy ride quality
>> Electric assist steering on 3.0si
>> Lack of storage space in cabin

OVERVIEW
BMW's sharp-edged Z4 entered the world as a successor to the curvy Z3 and first and foremost conceived as a soft-top roadster.

The Z3 was far more pose than performance but by the time the Z4 arrived in Australia in mid-2003, the sharper edges of its design were reflected in its driving characteristics -- it started to feel more like a proper two-seater sportscar. A significant makeover, including the arrival of an M version, occurred earlier this year and further developed the image.

That said, there's nothing like a small hardtop two-door to truly scream sportscar. Enter the Z4 Coupe... First proposed as a concept for a one-make motorsport series, the compact two-door was subsequently presented to the BMW board which decided it should become a roadgoing reality and the rest is history.

The press blurb calls the Z4 a "pocket GT" and reflecting its boy's toy credentials, just two models are on offer in Australia. The entry level is the Z4 Coupe 3.0si that starts at $87,900 for the six-speed manual (a six-speed Steptronic auto adds $2600) and topping off the range is the hairy-chested manual-only 3.2-litre Z4 M-Coupe priced from $127,200.

FEATURES
First up, strictly speaking, the Z4 Coupe is actually a three-door hatch with the rear glass lid lifting to reveal a half decent boot space that swallows 340 litres in the 3.0si version.

That said, styling is definitely all-coupe and where the Roadster's soft top doesn't look entirely integrated, the hardtop completes the lines that draw down its length from the base of the kidney grille. From any direction, this car looks a complete package and with both versions sitting on low-profile 18-inch alloys, it looks a potent package too.

The roof does more than provide weather protection as it also helps substantially increase the rigidity of the car compared to its soft-top kin aiding its handling potential. BMW says it is its stiffest road shell ever.

Inside, the aesthetics are no less attractive with the driver faced with a very thick-rimmed three-spoke steering wheel and BMW's familiar switchgear. As premium models, both versions are well specced with the 3.0-litre 3.0si coming standard with climate control, full leather trim, power windows, mirrors and heated sports seats, cruise control, remote locking, and a 10-speaker premium six-stack CD audio system.

In addition to this, the M version also gains -- apart from the obvious body kit and assorted interior and exterior cosmetics, sports suspension, and bigger engine -- parking assistance, an alarm, Xenon headlights, satnav, TV and a higher grade audio system that is THX certified. 

Although both models run on 18-inch wheels, they feature different tyre packages with the 3.0si using stiff walled but lower profile 225/40 front and 255/35 rear runflats while the M uses a conventional tyre with slightly higher profile 225/45 front and 255/40 rear rubber.

COMFORT
As a small two-seater space is at a premium though the Coupe does offer enough room to accommodate a fair swathe of the Aussie male population (BMW says the car will be purchased by guys predominently).

Once you have 'climbed' over the high sill, you drop into sports seats that are comfy and supportive with big side bolsters to help keep you in place. The M version has bigger bolstered seats than the 3.0si but both are fairly comprehensive wrap-arounds and perhaps just a fraction too narrow across the back.

The seats are fully adjustable but you would need to be seriously short of stature to require the height adjust. The headroom, while better than, say, an Alfa Brera is still snug. With a rake and reach adjustment for the steering column, getting the perfect driving position is easy.

The footwell is reasonably tight with the brake and clutch pedal in close proximity but they are well aligned so you are not likely to accidentally hit the wrong one.

What is lacking in the interior however are storage cubbies. There is one 10-litre bin in the rear bulkhead between the seats, but the doorbins are next to useless and you struggle to find somewhere secure to place a mobile (for instance).

SAFETY
As a high performance Coupe, the Z4 is not lacking in safety gear but first and foremost a great deal of the safety comes from its incredibly stiff and rigid body and very well balanced 50/50 weight distribution.

Both models feature driver and passenger front and side airbags while the standard stability control (DSC) offers three modes of operation: all systems on, traction control only which allows a higher degree of slippage before being activated or fully deactivated.

The DSC works in conjunction with the anti-lock brakes that also feature electronic brake force distribution and cornering brake control and a further five features aimed at ensuring the car remains in control at all times. These include brake pretensioning, brake drying, hill start assistance, brake fade compensation and a soft stop feature.

The brakes on the 3.0si use 325mm front and 294mm rear ventilated discs while the M Coupe gets its brake hardware from the M3 CSL and uses drilled and ventilated 345mm front and 328mm rear discs. Can you spell s-t-o-p!!!

MECHANICAL
Under the bonnet of the Z4 3.0si Coupe resides BMW's superb latest 3.0-litre straight six engine that can also be found in the 1, 3 and 5 series cars. In the Z4 Coupe it generates peak power of 195kW at 6600rpm and maximum torque of 315Nm at 2750rpm.

The M Coupe's engine is the same as that found in the previous generation M3 models and from its 3.2-litres it develops maximum outputs of 252kW at 7900rpm and 365Nm at 4900rpm.

Both drive the rear wheels through a six-speed manual gearbox with the 3.0si also available with an optional six-speed Steptronic automatic with manual sequential shift mode actuated by steering wheel mounted paddles.

Like their Roadster brethren, each shares a spring strut front end and central arm rear axle with the sports-tuned M-version sitting 10mm lower with firmer spring and damper rates. The M-version also gains the trademark variable M differential that can deliver between 0-100 per cent of power across the rear axle.

The other main mechanical difference between the two models lies in the steering with the 3.0si using electric power assistance while the M retains a hydraulic power assistance with a tighter ratio.

COMPETITORS
As a small sports performance coupe, the Z4 clearly has Porsche's Boxster-based Cayman in its sights as a main rival with that car sitting, performance-wise, slightly above the base 3.0si BMW model. The entry level Cayman will cost you from $118,000 and its 2.7-litre powerplant generates 180kW and 273Nm. The Cayman S generates 217kW and 340Nm from its 3.4-litre flat six but with a starting price of $148,500, it is significantly more expensive than even the M Coupe.

Closer to the Z4 in price is the Mercedes SLK that offers two V6 models that in terms of outputs sit either side of the Z4 3.0si with the 3.0-litre SLK 280 delivering 170kW/300Nm and the 3.5-litre SLK 350 generating 200kW and 350Nm. Both are more expensive than the Beemer at $101,400 and $114,400 but both are fitted with a seven speed automatic and offer a folding steel roof.

The M Coupe rival in the Benz stable is the AMG-tuned SLK55 that is powered by a 265kW/510Nm 5.4-litre V8 and is priced from $163,400 but despite the extra grunt, it only betters the BMW in a 0-100kmh sprint by a claimed 0.2 seconds with the latter hitting the ton in 5.0 seconds flat.

Audi will also have a rival for the Z4 Coupe when the new TT arrives mid next year with the top of the range 184kW/320Nm 3.2-litre V6 quattro model potentially taking the challenge to the Z4 3.0si.

And over a very serious 600km half-lap of Tasmania from Hobart across to the west coast and up back to Launceston via Cradle Mountain, we got the opportunity to get a very good taste of exactly what intent these two cars have.

The 3.0si is obviously the lesser endowed of the two but with BMW 's superb 3.0-litre straight six under the bonnet it is certainly no wallflower. A claimed 0-100kmh in 5.7sec seems perfectly achievable. Push hard on the accelerator, and the smooth free-spinning engine rapidly delivers its all in a long continuous linear fashion as it keeps pushing from about 2000rpm right through to the seven-grand redline.

Keep it revving anywhere over 3000rpm through judicious use of the slightly notchy six-speed manual box and the response from throttle input is immediate and urgent. But the beauty of this engine is its very broad spread of torque which means that should you desire, you can drive it with a lazy left arm and let the torque do its work when needed. 

Which is not such a bad idea as unfortunately, the steering needs your constant and undivided attention. It might turn in reasonably sharply but with its electric assistance it is very fidgety and needs regular readjustment along a straight line. Throw in some irregular road surfaces and without a firm grip on the wheel, the car will tend to follow every undulation and camber in the tarmac.

Although the 3.0si isn't sitting on a "sports" suspension, the ride is very firm and while low speed compliance is reasonable, it does redirect every nuance in the road surface through the seat base at higher speeds. The average ride quality is not helped by the very low profile stiff-walled run flat tyres that still lack the suppleness of regular tyres.

As a car to be driven fairly hard though, the Z4 3.0si delivers -- within reason and in reality, up to a point that few owners are going to exceed.

Faced with a tight twisting tarmac, you can push through at enthusiastic speeds with the extremely tight body enabling the car to sit flat and firm on the road. Seemingly you might think that as the next bend approaches, you can push even harder but as the cornering speeds rise, so to does the nervousness in the car -- and subsequently the driver.

The combination of a short wheelbase, lightweight rigid body and very stiff suspension means that push too hard on cut up corners and it doesn’t take much for the rear end to start to stumble and skip. The well-calibrated stability and traction control are reasonably quick to bring things back into line and, in the event of extreme action, the brakes do a magnificent job of pulling the car up.

Step up into the M-Coupe and you are in for a raw and even more involving experience that starts to deliver a rush to the head from the minute you prod the throttle. The engine is as strong as the 3.0-litre off the line and at around 2000rpm, both are generating about 280Nm of torque. But where the 3.0si peaks at 2750rpm, the 3.2-litre M engine just keeps getting stronger with the torque peaking at a high 4900rpm.

Keep the throttle planted and it just keeps on pushing right through to the power peak at nearly 8000rpm.

In some respects it doesn't actually feel as linear and flexible as the 3.0-litre but perhaps that is because it offers so much more at the top end. And if you want to play hard, it needs to be spinning between 4000rpm and 8000rpm.

Like the 3.0-litre there is a slight notchiness to the gearshift and despite sitting on a firmer lowered stiffer sports suspension, there doesn’t seem a great deal of difference in the ride quality, thanks to the M Coupe riding on regular, and slightly higher profile, rubber. In fact, in some instances over particularly rough roads, it actually felt slightly more compliant and comfortable.

It also feels more solid on the road, which is due to a number of factors. For a start the M weighs in with an extra 100kg on the tab and it also runs with conventional hydraulic assistance for the steering. The M turns in sharply and smoothly with much greater feel and feedback, although this is partly damped by the enormously thick rim of the wheel.

These things combined with the limpet like grip from the tyres, give the M a much greater surefootedness and the confidence to push it a bit harder. But again as the outer limits are approached, it still has a propensity to get a bit twitchy in the tail if you get too silly.

Both cars can be fun to drive and there is no doubt about the adrenaline rush that you get with the engines revving hard winding through a glorious stretch of twisting tarmac but always there is a lingering sense that if you are not careful, they could bite back.

The press blurb may have suggested the Z4 Coupe was a "pocket GT" but Grand Touring is not what they are about. These are both cars that require constant effort and concentration to drive -- at any speed -- being particularly busy at the wheel.

Where such behaviour may be welcome when pushing hard through the tight twisting roads that wind through the mountains of western Tasmania, it might not be what you would want to live with on a daily grind through the urban traffic jams.

On first impressions, the Z4 Coupe fits the bill for weekend warriors but, as a true sportscar should be, might be just too edgy and wearying to be used as a daily transport.