2009 BMW Z4 sDrive35i Roadster Road Test Review

The Z4's sound system offers a high level of sound quality, making it the perfect alternative to the 'sonorous six', when traffic impedes progress or you just want to relax.

Passive safety features include four airbags (front and side/thorax), along with new seat-belt-tightening technology. A pair of fixed roll bars behind the seats, a very stiff bodyshell and strengthened windscreen pillars offer further accident protection.

The Z4's active safety features arsenal includes electronic stability and traction control, anti-lock brakes, and cornering brake control.

Mechanical Package

The sDrive35i's twin turbo 3.0-litre six is good for 225kW and a useful 400Nm (from just 1300rpm). According to BMW its enough to propel the manual sDrive35i from 0-100 km/h in 5.2 seconds and the double clutch equipped car in just 5.1 seconds.

A six-speed manual is standard in the sDrive35i, but our test car was equipped with the optional ($3,500) double clutch seven-speed, enabling lightning fast and almost seamless gearchanges.

The manual officially returns a combined cycle economy figure of 9.8 l/100km while the double-clutch betters that by 0.4 l/100km. There is little between the two in CO2 emissions, with the manual generating 228g/km and the double-clutch 219g/km.

BMW's Dynamic Drive Control (DDC) is featured and allows the driver to select between Normal, Sport and Sport+ options.

The different settings are software controlled and change throttle response, steering response, gearshift speeds (dual-clutch equipped cars) and the stability control thresholds.

The standard electronic differential lock negates the fitment of a limited slip differential, but BMW engineers have managed to get around this by programing the Dynamic Stability Control to brake the wheel that spins, and send drive to the wheel that has better traction.

The Z4's suspension has been revised and features front struts that combine with a double-joint tie-bar system, made almost entirely from aluminium.

The rear suspension is independent and features longitudinal arms attached to the Z4's chassis and track control arms that attach to the axle's subframe.

An optional Adaptive M suspension package is available across the Z4 range. It reduces ride height by 10mm and introduces electronically controlled dampers, that work in sync with Dynamic Drive Control (DDC), adding a further dimension to the 'selectable drive experience'.

Braking duties in the sDrive35i are handled by 348mm front and 324mm rear brake discs, and aluminium callipers.

The Drive

The Z4 is an experience akin to automotive theatre. Drop down into the snug cabin for the first time and you're confronted with an exquisite mix of leather and wood, along with a bonnet that stretches decadently into the distance.

Of course the fact that you sit low, just forward of the rear axle, seemingly inches from the ground, just adds to the drama.

Punch the starter button and with a mechanical whirr the 3.0-litre twin-turbo fires to life. It's all creamy smooth BMW straight-six, with just enough metallic raspiness to hint at the measure of intent on tap.

The stumpy controller for the dual-clutch gearbox is easy to use, once you are accustomed to clicking the side button with your thumb (necessary to engage reverse or drive). If you prefer selecting gears yourself, then the controller can be pushed across into Manual mode.

Once in manual mode, you upshift by bumping the controller backwards, with downchanges requiring a forward push. It's intuitive to use and on the right road an absolute riot.

On the other hand you can use the steering-wheel mounted buttons to change gears, but its an altogether more confusing, and less rewarding experience.

Engaging sport mode ('DS' Sports Drive) shifts the game along, with faster gear changes, and a pleasingly heady exhaust sound-track.

The force fed straight-six is turbine smooth, and in the Z4, thanks to some neat exhaust tuning, it has found its voice. An altogether pleasingly gruff little number, there is plenty of smile inducing pop and crackle at low speed and on the overun.

In either of the sports modes, the pops and crackles combine with a whoofly 'braaaap' between upshifts and perfectly timed throttle-blips on downchanges.

BMW's dual-clutch gearbox is hard to fault and even had this dedicated manual shifter thinking that, yes, this just may be the future.

It feels like a 'tightly wound' automatic. There is nary a hint of low speed hesitation or juddering, just smooth, precise gear changes handled with 'Swiss Watch' precision.