Following on from the saloon and estate, the BMW 3-Series Coupe joins the range from late September 2006.

With a long wheelbase, laid-back A-pillars and a stretched, flowing roofline giving the coupe a genuinely graceful profile, it's a car that looks better in the metal than in pictures - primarily because the rear flanks have stronger 'shoulders' than they appear two-dimensionally. The car just looks tougher, stronger and better planted in the metal. Indeed, viewed from the rear three-quarter, the coupe has shades of the old 8-Series about it, particularly with those large wraparound tail lights.

When it goes on sale, the coupe will be offered with two straight-six petrol engines, a 218bhp 2.5-litre or a 306bhp 3.0-litre twin-turbo. The former will cost £28,090 and the latter £33,420, putting the latest BMW coupe directly up against Nissan's 350 Z, Alfa Romeo's Brera Q4 and V6 versions of Audi's next TT, which goes on sale around the same time as the BMW.

There's big news under the bonnet, too. It's the first time BMW has offered a twin-turbo straight-six petrol, albeit not the first time the company has offered a turbo petrol (1973 2002 Turbo). The 335i uses a 3.0-litre power plant, with each of the two turbos feeding three cylinders. Maximum torque of 295lb-ft is developed from a remarkably low 1,300rpm. The headline figures are 0-62mph in 5.5 seconds and a limited top speed of 155mph. Fuel consumption is a claimed 29.7mpg overall, which is pretty good going for a 300-plus bhp engine. And BMW says that its six weighs 70kg less than a typical V8 with similar power.

When it goes on sale, the coupe will be offered with two straight-six petrol engines, a 218bhp 2.5-litre or a 306bhp 3.0-litre twin-turbo. The former will cost £28,090 and the latter £33,420, putting the latest BMW coupe directly up against Nissan's 350 Z, Alfa Romeo's Brera Q4 and V6 versions of Audi's next TT, which goes on sale around the same time as the BMW.

We drove a twin-turbo-equipped coupe on the mountain passes around Innsbruck. The first thing that struck me, as a veteran of turbo lag going back to mental Saab Aeros and early 911 Turbos, was the total absence of that pause before the storm. In fact, it would have been easy to believe that the engine was just a large capacity, non-turbo unit. That's partly because the turbochargers are relatively small, meaning there's not much in the way of inertia to overcome - and then there's all that low-down torque to launch you smartly off the line.

That said, this engine isn't as ferocious as the figures might suggest: it's very swift as opposed to oh-my-god punchy. In fact, first acquaintance with BMW's fantastic 3.0-litre twin-turbo diesel will leave most people short of breathless superlatives while the 335i is very impressive but nothing more.

The 335i comes standard with a six-speed manual, which has a direct, smooth and quick action. But it doesn't really suit the Grand Touring character of the coupe - much better to specify the optional six-speed automatic transmission, which is one of the very best slush boxes we've ever tried. The highlights are an incredibly smooth shift response, extremely quick reaction to kickdown (40% better than most autos, says BMW) and a shift programme that adapts to how the car is being driven. It can even determine if the car is being driven downhill and will select a lower gear for engine braking it that's the case. There are steering-wheel mounted shift levers for manual cog-swapping - these are fat lumps of aluminium, very nicely done indeed. And they work well enough, but frankly, this 'box is so responsive we imagine most drivers won't bother.

The driving experience is just as you'd expect and, without prejudging how well the Audi TT will drive in comparison, we'd hazard that the BMW will remain best in class. The only frustration is the lack of a limited slip differential (LSD), which isn't even an optional extra. So take on a tight corner with the power on and just the inside wheel will break grip and spin. Which makes power-on oversteer much more difficult.

As with the saloon and estate, BMW's Active Steering is available on the coupe. The system changes the steering ratio depending on the speed of the car, the idea being to make the steering quicker and more agile at lower speeds, while delivering more stability at high speed. We'd recommend that you give it a miss, though. It doesn't feel any more stable at high speed than the standard set-up and, at lower speeds over challenging roads, it can be difficult to judge exactly how much lock you need for a given corner. The standard steering set-up delivers excellent feedback, although it does feel a bit heavy at low speeds, not something we'd noticed on the saloon and estate.

For a car that's more about touring than the full-on sports car experience, the coupe's ride is too firmly damped, especially at low speeds. We'd point to the standard-fit run-flat tyres as the chief suspect, even though the saloon we road tested didn't seem to have this issue.