We like
Exterior styling, engine power and response, fuel economy, body rigidity, retention of sporting credential despite weight gain over coupe, exhaust growl with roof down, remote opening for windows/roof, improved ride of latest-generation run-flat tyres, improved iDrive useability from ‘favourites’ buttons

Room for improvement
Some roof rattle, remote closing of roof a $1250 option, costly metallic paint ($1600)

IT WAS more a question of when, rather than if, BMW’s 3 Convertible would have a folding metal roof.

Pioneered by the Mercedes-Benz SL and SLK models, appearing on affordable baby cars like the Peugeot 207 CC and the discontinued Holden Tigra and Daihatsu Copen, and now on 3 Series Convertible rivals like the Volkswagen Eos and upcoming Focus CC, a folding hard-top even appears on the Roadster Coupe version of Mazda's iconic MX-5 - the king of all roadsters.

And why not? The benefits are certainly convincing: increased security and sound insulation over a canvas roof and, of course, the ‘wow factor’ of the roof operation itself, which is certain to impress onlookers.

Of course, there are drawbacks too. The additional weight diminishes handling dynamics, there is even greater loss of boot space and there is the ‘big bum’ syndrome caused by the long boot and steep shoulder line of many coupe-convertibles.

With these challenges in mind, one can only imagine the shouting matches between BMW’s exterior designers and engineers. It seems the latter returned to the office sporting blackened eyes and bruised egos, because the E93 successfully packages typical BMW engineering depth within a cohesively styled convertible body that remains true to traditional BMW design proportions.

Now in its fourth generation, the 3 Series Convertible marks BMW’s first hard-top convertible and comprises signature BMW exterior styling – as rigorously emphasised in the design brief – including a low, sleek and virtually flat shoulder line that rises no more than 20mm from nose to tail (as per previous soft-top iterations), a short boot and, of course, the ‘Hofmeister kick’ curve at the bottom of the C-pillar window line – a BMW convertible first.

With the exception of the all-new Volvo C70, its main rivals, including the Audi A4 Cabriolet, Mercedes-Benz CLK and Saab 9-3, still use electrically-operated fabric roofs, but most will be replaced by completely new models in the future, possibly in hard-top guise.

The BMW hard-top is a three-section system that the company claims folds into a similar space required by a canvas roof.

Seeing the new 3 Series Convertible on the road – for the first few times, anyway – you would probably assume it was a coupe. Apart from the third brake light integrated into the bootlid, two trim bars covering the functional elements of the roof mechanism and slightly different-shaped C-pillars, there is not much to distinguish between the two-door 3 Series derivatives.

Only the doors and body panels forward of the A-pillar are shared with the coupe, but they are almost identical in terms of proportions, although the Convertible is 9mm taller and tips the scales at some 210kg heavier (auto: 1750kg manual: 1735kg). This is a result of extra floorpan reinforcement and the roof mechanism.

Opting for a steel roof over canvas has improved rear visibility thanks to a larger glass area, claimed to be 30 and 38 per cent bigger at the side and rear windows respectively. With the roof up, rear passengers can now appreciate a proper view rather than having to peer through an area resembling an aeroplane window.

If your passengers are eager and weather permits, you’ll be pretty keen to drop the roof and enjoy that open-air motoring experience.

The roof takes 22 seconds to open by either a button near the handbrake lever, or by holding the unlock button of the key-fob for the duration of the opening process – a trick certain to stun a crowd as you approach the car.

It closes in 23 seconds, but only via the centre console button unless you take the $1250 ‘Comfort Access’ option.

This package also enables you to unlock and start the engine without removing the key from your pocket or handbag and, via the key-fob, open the double-hinged boot the opposite way while the lower roof section is moved to an interim position, allowing for more convenient storage access for bulkier objects. This takes a total of ten seconds.

The new Convertible provides 350 litres of boot capacity with the roof closed and 210 litres with it open. By comparison, a 3 Series sedan offers 450 litres, whereas the previous (fabric-roofed) E46 3 Series convertible offered 300 litres with the roof closed and 260 litres with it open.

After a decent stint at the local supermarket, we managed to stow about eight bags of shopping with the roof open.

Further storage can be had by folding the one-piece rear-seat backrest to provide a flat surface for objects without risking damage to the leather, while a load-through system from the boot to the cabin allows for longer items such as golf bags and skis.

With an identical standard equipment list (though the convertible comes at a $12,000 premium over the coupe), the 3 Series siblings have virtually identical interiors.

Both are strictly four-seaters and share the same full-length centre console running from the dash through to the back seat, providing storage areas and cup-holders rather than space for a centre rear-seat passenger.

Like the previous model, the front seatbelts are integrated into the convertible’s seats (as opposed to the Coupe’s novelty electrically-retractable seatbelt arm) and, most notably, the iDrive – the ever-controversial multi-function system that does away with dash buttons – now adds eight programmable ‘Favourite’ buttons.

Appearing like radio presets, these handy touch-sensitive buttons eliminate the need to fiddle through the iDrive’s menus to do many tasks and, most importantly, they help to keep your eyes on the road.

The presets can be programmed to retrieve favourite radio stations, regularly dialled phone numbers (using the Bluetooth integration) and route guidance destinations – although we wonder how many users need to program a regular destination. Instead, a single button to display the map would be most useful, rather than having to work through the iDrive menu.

Other technologies include a rollover system incorporated into the rear head restraints that relies on sensors that permanently monitor vertical and horizontal movements, plus automatic-dipping headlights, cruise control with a brake function to maintain a pre-set speed when running downhill, ‘Soft Stop’ (which prevents the final jolt when coming to a complete stop), a hill-holder function and leather upholstery that reflects infrared rays in direct sunlight and reduces the surface temperature by up to 20 degrees.

Like the coupe, the convertible is surprisingly roomy. Apart from electric front seats that move too slowly (it's very frustrating waiting for rear seat access when it’s raining), we did not receive any other complaints from our three adult passengers about head or legroom. It must also be said that the (heated) front seats are particularly comfortable, offering a multitude of adjustments.

Cruising the Yarra Valley, we were expecting a harsh ride on B-grade roads, but the fourth-generation run-flat tyres simply did not make themselves known in the way we have recently experienced in various other BMW models.

So has BMW finally addressed its two major criticisms – iDrive and run-flat tyres? It appears so.

The 335i Convertible receives the brilliant 3.0-litre twin-turbo inline six-cylinder engine first seen in 3 Coupe.

With each low-blowing turbocharger breathing into three cylinders, the engine pulls effortlessly with virtually no turbo lag while producing 225kW at 5800rpm and a flexible 400Nm of torque, available between a ridiculously low 1300rpm and 5000rpm.

But it is only now, in the convertible, that 335i drivers can experience the engine growl and accompanying exhaust symphony in full – with the roof down.

Despite its extra 210kg, the 335i Convertible still excels at perhaps the three most critical prerequisites for 3 Series Convertible buyers (apart from styling): performance, handling and economy.

While it may not have the standard sports suspension tuning of the coupe, it retains a 50:50 weight distribution and a level of sporting dynamics that is generally unmatched in the four-seater convertible segment.

BMW claims the new Convertible’s body rigidity is 50 per cent stiffer than its predecessor's and, cutting through twisty roads at 100km/h with the roof down, the A-pillar and windscreen were rock solid, as was the body. We did, however, experience some rattles where the lower roof section meets the body.

Acceleration from 0-100km/h takes six seconds when mated to the optional six-speed automatic (which sports new electronics for 40 per cent faster shifts), while the manual gets over the line in 5.8 seconds. By comparison, the coupe manages 5.7 and 5.5 seconds respectively.

While we did not achieve the same 10.0L/100km fuel consumption average as we did in the 335i Coupe (which was subjected to more country driving), we still managed a respectable 11.4L/100km. Some enthusiastic lead-footing saw a jump to 13.0L/100km.

Like any convertible, the 3 Series drop-top is not quite as sharply focused as its fixed-roof sibling, but offers a versatile open-motoring experience while balancing the benefits of a folding metal-roof, a strict design brief and, most importantly, typically top-shelf BMW driving dynamics.