BMW Z4 sDrive 35is (2009) at Detroit motor show 2010

These are the first official pictures of the new high-performance BMW Z4 sDrive 35is, unveiled today at the Detroit motor show. A bit of a mouthful (that's BMW's new nomenclature for you), but it's essentially the fastest, hardest Z4 to date since the recently departed M roadster curled over and died.

The Z4 sDrive 35is uses Munich's existing 3.0-litre twin-turbo straight six, tweaked to produce 335bhp and 332lb ft of the twisty stuff all the way from 1400-4500rpm. That's one flat torque curve, and a 29bhp jump over the regular sDrive35i. The six-pot is mated to BMW's paddle-controlled seven-speed twin-clutch transmission, driving the rear wheels.

Subtle body addenda denote this as the sportiest Z4: an M Aerodynamics Package includes 18in light alloys (19s are an option) and a 10mm drop in ride height, while a new bumper includes matt aluminium horizontal bars at the front and a chunked-up rear bumper/diffuser assembly. All typically Germanic, subtle oneupmanship to justify the step up in price.

Thanks to a brief overboost function for overtaking, you'll waft on a tsunami of 369lb ft of twist for short bursts. So 0-62mph is claimed to take just 4.8 seconds. Top speed is, naturally, limited to 155mph.

CO2 emissions stand at 210g/km and the quoted combined economy figures are 31.4mpg (the same figure as the regular Z4 sDrive 35i equipped with the Sport Automatic transmission).

Well, we already rate the Z4 as a slick two-seat roadster, albeit one that's lost some of the sportiness of the outgoing model. The latest Z4 is undeniably more grown-up, more refined. More like the Merc SLK.

The sDrive 35is should address our criticisims. The emphasis is definitely on sportiness: there's a launch control function, M Sports suspension pack and even an exhaust system with special flaps in the silencers to adjust the engine noise depending on your driving style.

The Z4 sDrive 35is makes its world debut at the 2010 Detroit auto show – alongside the launch of the M Sport package for all other Z4s. We'll drive the new sporty model in spring 2010; full details to follow then.

Will there be a full M-spec Z4 to follow? Watch this space. Until now, the sDrive 35is is the halfway house.

By Tim Pollard