Revealed: BMW’s drop-top 4 Series

BMW has revealed the next generation of its 3 Series convertible, featuring a car that is roomier, quieter and promises better driving dynamics than the model it replaces.

The all-new 4 Series Convertible – the two-door, tin-lidded drop top has moved its name to an even number in line with the rest of the BMW-badged two-door cars – is slightly longer and wider than the car it replaces, but sits on a significantly stretched wheelbase. It looks almost identical to the 4 Series Coupe on which it is based.

However, comfort has also come under the same scrutiny as advances to the convertible’s dynamics, with improved roof linings that perform much better at insulating road noise from the cabin, and a bigger boot when the roof is stowed.

Due to be officially unveiled at next month’s Los Angeles motor show and due in Australia by the end of autumn next year, the 4 Series Convertible also keeps the pillarless two-door look if the roof is kept in place and the windows lowered.

A new sound-absorbing headliner reduces wind noise by up to 2dB compared with its predecessor.

Similar to the model it replaces, though, the top will take about 20 seconds to fold away under the bootlid, but at least it can be raised or lowered at speeds of up to 18km/h.

Boot space crunches from 370 litres to a still useable 220L – 20L more than the model it replaces. The stowed roof will tilt up, too, to make loading things into the space much easier.

The new drop-top does get a new feature, though – optional three-setting neck warmers built in under the headrests that waft warm air at the press of a button. Combined with a redesigned wind deflector that stows in behind the rear seats, and not the boot, the 4 Series promises a much more serene cabin with the roof down.

As well, the front seatbelts are integrated into the seat backs, replacing the 3 Series’ version that fixed behind the door and included an extending arm that helped with access.

The 4 Series is expected to follow the coupe’s trim specifications, which include Sport Line, Luxury Line and M Sport.

Engines range between either a turbocharged 420d diesel or 428i petrol four-cylinder unit, or a turbocharged 3.0-litre in-line six-cylinder 435i.

Outputs range from 135kW to 225kW of power.

Gearbox choices are either a six-speed manual, or an eight-speed automatic transmission. The auto includes a function that decouples it from the engine at speeds above 50km/h to allow the convertible to coast along, saving fuel.

It also includes what BMW calls a Proactive Driving Assistant that can warn the driver to back off the throttle when approaching a corner or a lower speed zone.

The 4 Series Convertible also joins the growing fleet of cars that are able to recognise when a pedestrian steps in front of the car, automatically priming the brakes to help either avoid or minimise a collision.

The 4 Series Convertible will also use BMW’s latest fatigue detection system that is able to sense when a driver needs a break from behind the wheel.