When BMW launched its second-gen Z4 last year, we were disappointed to find that it had apparently abandoned its predecessor's edgy, taut feel in a bid to find more mainstream appeal. The more relaxed nature and folding hard-top roof were enough for us to question whether Munich's popular two-seater had gone soft.
We needn't have worried, because this new sDrive35iS variant shows that BMW is not about to let its roadster slip off the radar of enthusiasts seeking an alternative to the Merc SLK and Nissan 370Z. Sporting a body kit developed at BMW's M division, the sDrive35iS looks more aggressive than standard Z4s (although from now on buyers will be able to option all models with the new look). It also wears a new set of 18in. wheels that combine with a lower ride height to fill out the wheel arches more convincingly.
At the heart of the new car is a reworked version of BMW's twin-turbo 3.0-liter straight six engine, which delivers a significant performance edge over the Z4 sDrive35i – without any increase in fuel consumption. Power climbs from 302 to 335hp at 5900rpm, and torque jumps from 295 to 332lb-ft at just 1500rpm. Thanks to a new over-boost function, it even increases to 371lb-ft for short bursts of full-throttle acceleration.
At 3.362lbs, the Z4 sDrive35iS is still no lightweight, but with a power-to-weight ratio of 220hp per ton it's surprisingly quick in the right conditions. BMW claims 0-62mph in 4.8sec, eclipsing the Boxster S's time by half a second. The reworked engine is super-responsive, with the sort of free-revving nature that makes it feel more like a normally aspirated unit than a turbocharged one. It also produces a wonderful soundtrack.
Channeling the engine's added reserves back to the rear wheels is BMW's 7-speed dual-clutch transmission. It's a little hesitant around town, but on the open road the shifts are more decisive and faster – especially so if you're in the Z4's Sport+ mode for engine, throttle and gearbox mapping. For added entertainment and a smoother transition when closing down hard into corners, the new gearbox also introduces a hearty blip of the throttle on downchanges.
The sDrive35iS sits 10mm lower than other Z4 models and gets beefed-up anti-roll bars with firmer springs and noticeably stiffer electronically controlled dampers. On smooth German roads, the ride quality was very impressive, given that it uses run-flat tires – firm but never harsh. At low speeds around town and higher speeds on the open road the MacPherson strut (front) and multi-link (rear) suspension is well controlled and boast sufficient compliance for even nasty surfaces.
But it's the handling that has really benefited. The new BMW changes direction smartly, stays flat and feels encouraging on the right roads. The electro-mechanical steering is nicely weighted, quick to respond and eager to self-center.
The inherent balance of the chassis makes the new Z4 a blast to push hard near the limits of adhesion. The cornering attitude is neutral and grip remains strong up to very high cornering speeds. In Sport+ mode, the dynamic stability control system is disengaged entirely, but while you can unsettle the rear with sufficient provocation, the breakaway is progressive enough for you to control it on the throttle.
Inside, the cabin includes M division styling touches such as a new steering wheel – albeit with sadly fiddly two-way paddle shifters. The car's newly revised seats are great, offering a better driving position and lateral support.
Roof up or roof down, the Z4 sDrive35iS confirms BMW's commitment to the enthusiast driver. It's just a pity that at a steep $62,000, it is even more expensive than the old Z4 M roadster.