We like
Body rigidity, balance, grip, handling, performance, bigger interior and boot, roof operation, equipment

Room for improvement
Price, steering, polarising styling, ride comfort, no spare tyre, rear three-quarter blind spot

THIS is a much more serious sports car than the Z3. For openers, there’s no four-cylinder version and for seconds, the opening price barely dips below $80,000, even in the entry-level 2.5-litre version.

The Z4 also comes to market bearing the signature of BMW stylist Chris Bangle’s team of out-there designers. Its long-bonnet, stub-tail look is arresting, its origami creases and curves - in terms of what can be wrought from a piece of metal - astonishing.

That the Z4 has presence is absolutely without question. And, as is usually the case with such bold shapes, the detractors seem to be equal in numbers to those who like it. The BMW is a polarizing car.

At the same time it is a bigger, more accommodating sports convertible than the Z3, with more cockpit space and a larger boot.

Yet the concept is the same: front-mounted in-line engine driving the rear wheels, independent suspension derived from the 3 Series and a power operated folding roof.

The driver and passenger sit back, and low, just behind the centre of the car, feeling quite snug. Combined with the Z4’s 50-50 fore-aft weight distribution, this gives the driver the feeling of being at the centre of the action.

The confronting stylistic challenges continue into the interior. The distinguishing feature is a sweeping, full-width burnished plastic panel departing from the common driver wraparound cockpit style.

Two large dials in a hooded surround contain speedo and tacho, while regular controls, plus vents for the climate control air-conditioning, are located in the centre.

Two optional satellite-navigation systems are offered: a basic set-up minus the usual map display and the more familiar arrangement with a pop-up display screen on top of the dash.

Our test 3.0-litre Z4 picked up the six-speed manual transmission that comes as standard with this engine (the 2.5-litre gets five speeds only – both engines can be also mated to a six-speed auto transmission) as well as larger, optional 18-inch alloy wheels and sports suspension.

Z4s at either 2.5 or 3.0-litre level are well equipped with leather-trimmed, heated and power adjusted seats, cruise control, trip computer and a fully-trimmed convertible roof.

The 3.0-litre also gets a more punchy sound system, complete with 11 speakers, that adds muscle to just about any style of music you care to play.

But it’s the driveline that is important with the Z4 and, particularly in the case of the 3.0-litre, there’s a pretty formidable power-weight ratio to work with.

The twin-camshaft, 24-valve, variable valve timing (VANOS) six-cylinder is basically in the same tune as it is when used elsewhere in the BMW range (3 Series, 5 Series), with 170kW and a strong 300Nm of torque. Combined with the Z4’s relatively low weight of 1290kg, this means there is always a decent serve of acceleration on hand.

BMW claims 0 to 100km/h acceleration of 5.9 seconds, which places it quite squarely as a leader among its peers.

The power is delivered consistently across the rpm band, too, with plenty of punch available from low speeds and an always adequate surge – helped by the long-stroke design and, particularly, the nicely-spaced ratios in the six-speed gearbox - for accelerating hard out of corners.

In fact, not an awful number of cars in the category will touch it, including Porsche's Boxster - and you'll have to pay significantly more for the 3.2-litre Boxster S to go much quicker.

Then there’s the sound. What is nicely aural but suitably muted in BMW sedans becomes quite hard-edged and authoritative in the Z4. Even when cruising in the lower part of the rpm band, the inline six has a lovely grumble designed to warm the hearts of those who love sports cars.

The shortcoming, particularly when larger wheels and sports suspension are optioned, is that the Z4 does not like anything less than a perfectly smooth road surface.

On a racetrack the Z4 shows excellent balance (thanks to that perfect weight distribution), outstanding brakes and a tenacious grip. On a regular road, that is all compromised by its tendency to be influenced by small bumps and irregularities that mean holding it in a straight line is a chore.

Driving an optioned-up Z4 on a country road is not a relaxing experience, even if it has the potential to be a fast one. The almost-primitive behaviour feels HSV Commodore-like.

The trick, if you’re intending to use your Z4 for, say, the odd club race, is to have two sets of wheels store the big ones away during the week, then bolt them on when you’re heading out to the racetrack.

The standard 17-inch wheels, on the other hand, will deliver a more comfortable ride, easier steering on rough roads and none-too-shabby handling and roadholding on your regular workaday week. And, if you still choose to option up with the sports suspension, the negative side effects will be less noticeable.

Another thing that is disadvantaged by wide wheels and sports suspensions is BMW’s Dynamic Drive Control switch that not only sharpens up the engine response, but also lessens steering assistance to give a generally more urgent feel.

This it probably does with standard footwear and spring settings, but in our test car it only exacerbated the car’s vulnerability to dips, dives and bumps in the road.

In terms of livability the Z4 scores better than the outgoing Z3. The cockpit is roomier, and more low-slung for a nice secure feel, and the boot, although still relatively small, will hold a few more bits of luggage. The Z4’s run-flat tyres mean there’s no spare, which also helps.

The soft-top folds in less than 10 seconds, which makes it one of the fastest in town (although Honda claims about six seconds for its S2000) and there’s a glass rear window complete with demisting wires and a noticeable blind spot in the rear three-quarter.

Compared with its German rivals – Porsche Boxster, six-cylinder Mercedes SLK – the Z4 is well priced, comfortably below either - although still way in front of ascendant Japanese rivals like the Nissan 350Z and Honda S2000.

The looks equally repel and attract, with perhaps a tendency in most cases to err on the positive. Those who hate it really hate it those who love it really love it.

Get around that, and you’ve still got the issue of bump-steer to deal with, unless you go the safe route and avoid suspension and wheel options.

It will be interesting – really interesting – to see what happens when the M version of the Z4 comes along.