BMW's new Z4 Roadster is designed as a rival to Porsche's sublime Boxster. Its radical styling - a mix of deep creases, concave and convex curves, has created plenty of controversy, and, in a technological sense, it's loaded with cutting edge engineering. It's also very quick and seriously good fun to drive.
Value for money
Pricing
Two Z4 variants are presently available, powered by the 2.5 litre 141 kW straight six, or the 3.0 litre 170 kW engine, both with BMW's bi-VANOS variable valve timing.
The Z4 2.5i has a five-speed-manual gearbox; the 3.0i uses a six-speed. A five-speed-sequential automatic is a $2,600 option.
Prices are $78,500 for the Z4 2.5i and $92,000 for the 3.0i.
Warranty
Two years/unlimited kilometres, which is below average.
Standard features
Standard equipment on the Z4 3.0 (tested) includes an efficient three-dial airconditioning system, cruise control, rain sensing wipers, six-stack CD/10-speaker audio (with the stacker located in a bin behind the seats), trip computer, leather upholstery, front and side airbags plus Datadot security.
Retained value
The Z4's predecessor, the Z3, retains 60 per cent after three years, which is below average. The Z4 should do better - it's superior in nearly every respect to the Z3, most variants of which lacked the performance and/or dynamic ability to compete with the best in this class.
Ergonomics
The power adjustable, heated driver's seat has long travel. You feel like you're sitting only a few centimetres off the ground - which is true - and the driving position is spot on for this car's purpose.
The dash, slim and minimalist in style and layout, has a swathe of brushed aluminium running across it and delicate recessed instruments with pretty silver needles.
The wheel is height/reach adjustable and all controls are within easy reach.
You have no idea where the bonnet ends - apart from the knowledge that it's somewhere far away towards the horizon. A glass rear window allows clear rear vision, but the thick corners on the soft top create a substantial blind spot on either side when the roof is raised.
The soft top opens and closes in about ten seconds at the push of a button. It's breezy with the roof down - obviously, you say, but some other convertibles are calmer and quieter - so the optional wind deflector is probably a box worth ticking.
Innovation
Well, the styling - love it or hate it - is certainly different. BMW's straight six engines are at the forefront of technology, efficiency, smoothness and performance.
The Z4 features very sophisticated drivetrain management systems, including an electronic accelerator and Dynamic Stability Control.
The latter features Dynamic Traction Control, activated by a button on the dash. DTC allows you to balance the tail, as per a limited slip diff, instead of having the slightest break in traction immediately and aggressively accompanied by the stability control system taking over. DSC will still intervene if significant traction is lost.
Another button - Sport - selects a more energetic engine management map, so that the pedal is more responsive. It also adds weight to the steering by reducing its electric power assistance.
Run flat tyres - which, in the event of a puncture, can still be driven at low speed to a repair shop - are supplemented by a low pressure warning system. Run flats have their pros and cons - they're fine in the city, where the nearest tyre repairer or BMW dealer won't be too far away - but if you venture too far from the metropolitan area and suffer irreparable tyre damage you could find yourself stranded.
Safety
The Z4 scored four stars out of five in USNCAP crash tests.
Security
Data dots effectively mark many component of the car, which allows them to be traced. Remote central locking/immobiliser security is also provided.
Comfort
In the sports context, the Z4 driver's seat has a shortish cushion and inadequate backrest bolstering. It's firm, but reasonably comfortable on a long drive.
Space and practicality
There's plenty of space for two in the Z4's cabin. Useful cabin storage is almost non existent, but by convertible standards the boot is large. When the roof is raised, you can gain a little extra capacity.
Build and finish quality
You usually get a few squeaks, shakes and rattles in convertibles, due to the roofless body's compromised rigidity. No problems here though. The test car was extremely tight by convertible standards.
One severe impact from a potentially wheel breaking country road pothole did pop the front passenger door off its latch.
Overall fit and finish is not quite up to BMW's usual mark, with a few larger than usual and/or inconsistent gaps between some dash pieces, and doors that don't seem particularly solid.
On the road
Fuel efficiency
The Z4's relatively light weight (1290 kg), the efficiency of its engine, and six manual ratios produces excellent economy. Premium unleaded is recommended.
On the highway, the test car returned 7.9 litres/100 km. In town, the figure was 13.4 litres/100 km.
Performance
A good sports engine requires not only power, but responsiveness and flexibility as well. BMW's 3.0 litre six scores on all counts.
It will pull sixth gear from just over 1000 rpm, gets into stride at 2000, then spins with great energy and refinement to 6500, accompanied by a glorious sound.
The six-speed gearbox has well chosen ratios and a crisp, light, short throw action. The 3-2 shift can be a touch notchy. At 100 km/h in sixth, the 3.0 litre is pulling 2200 rpm.
In pure 0-100 km/h acceleration terms, the Z4 3.0 is a sub six seconds car - which means it is extremely quick.
Ride
On all but smooth bitumen the ride is quite harsh, and may for some be too unforgiving, though the test car had a much more uncompromising wheel/tyre package than standard, which contributed to this. The Z4 rolls over bumps rather than absorbing them.
Handling and steering
Even by roadster standards, the Z4 sits low to the ground. It has wide tracks, a long wheelbase and short overhangs. The suspension layout is based on the 3 Series, obviously tuned to a more aggressive purpose.
It is fitted with a greater percentage of alloy componentry to reduce unsprung weight and is supplemented with anti roll bars at both ends.
The 3.0i gets 17-inch alloy wheels, shod with 225/45 tyres. Our optioned up test car had 18-inch wheels, with 225/45 (front) and 255/35 (rear) Bridgestones.
On smooth roads, the Z4's dynamics are scalpel sharp and huge fun. The fact that you're almost sitting over the rear axles, allied with fine - but not perfect ? balance, no body roll and instant throttle response, makes the BMW easy to control and a joy to steer using both wheel and pedal.
The Z3 is less happy on undulating or rough surfaces, where the front wheels tramline excessively, and both ends kick hard on bumps.
The steering, while suitably direct, becomes quite light and flighty at highway speeds, where it also lacks feel on centre.
Tactility and precision can be improved by employing the Sport mode, but, overall, the high tech steering electronics are not particularly effective.
Braking
The ABS equipped brakes offer precise control at all pedal pressures and plenty of power.
Smoothness and quietness
The engine is beautifully smooth. In the 3.0 litre Z4 some engine noise is actually directed into the cabin, presumably through vents (which I could not find) somewhere under the dash.
The sound of the six is pleasurable. Less so is lots of tyre noise on coarse bitumen.
Summary
The Z3 was criticised as being too 'soft' to be a 'real' sports car. The same cannot be said of the Z4. It is a hard-edged, high tech performance machine. It's not perfect - the Boxster is closer to the holy grail - but the well priced Z4 is certainly a challenging, rewarding drive.
The writer of this report does not necessarily represent the views of the NRMA and this report is provided for you as an alternative to our own NRMA car reviews.
The writer of this report does not necessarily represent the views of the NRMA and this report is provided for you as an alternative to our own NRMA car reviews.
