Under the BMW’s bonnet, you’ll find a 154bhp 2.0-litre ‘TwinPower Turbo’ engine, which features a single twin-scroll turbo and variable valve lift and cam timing control. The combination of these technologies allows it to generate 177lb ft between 1250rpm and 4400rpm.
Although its modest power output translates to a tame but acceptable 0-62mph time of 7.9sec, its wide spread of torque means that the BMW feels flexible and punchy, even in higher gears.
It sounds moderately potent, too, with frequent flutters from its wastegate, audible turbo spooling and a satisfying burble on overrun.
There are no improvements in efficiency, though. The sDrive18i’s combined 41.5mpg and 159g/km of CO2 are the same as the 181bhp 20i’s and 241bhp 28i’s.
Drive is transmitted to the rear by a six-speed manual gearbox. It offers a decent selection of ratios and a short and swift shift action, allowing you to make good use of the power on offer, but its action is baulky and notchy.
The car we drove had several options, most notably 18-inch alloy wheels, adaptive M Sport suspension, sports seats and a Comfort pack that includes a rear wind deflector.
Although the Z4 has sporting pretensions, it doesn’t quite deliver on the road. The steering is precise and has enough weighting to avoid feeling nervous, and there’s plenty of grip, but it lacks feedback or consistency as you apply lock. This can make the BMW feel a little disconcerting around high-speed corners.
The ride, although firm, is tolerable. The BMW Z4’s brakes are also strong and progressive, the clutch smooth and the throttle precise and easily modulated. The quality and layout of the cabin is good, too, the kit levels are acceptable and the folding hard-top drops quickly at the press of a button. In terms of usability, the Z4 is excellent.