What's the news?

As sure as night follows day it was only a matter of time before the convertible version of the new BMW 4 Series followed the recently released 4 Series Coupé. Images of the car that replaces the 3 Series Convertible leaked on the web earlier in the week (leading to some puns about the 4 Series leaking - we see what you did there), but we can now bring you the full official details ahead of the car's public debut at the LA Auto Show next month ahead of going on sale in March 2014 with prices starting from £36,675.

Exterior

Images of the new model were leaked onto the web in the days before its official reveal so the similarity to the coupé model will have come as no surprise to many. The final piece of the jigsaw that was not immediately evident from the leaked images was the mechanism for the roof - would it be a soft or hard top affair?

Like the 3 Series Convertible it replaces, the new car will utilise a three-piece folding metal roof. Though similar in concept BMW says the new roof is a completely fresh design, with improved sound proofing and better aerodynamics helping to cut wind noise by two decibels with the roof up. Retracted the roof is stored in the boot which is rear hinged to allow its ingress.

To allow the 4 Series to accommodate larger items with the roof down BMW has fitted a system whereby the load and unload buttons will pivot the stored roof and move it upwards. It still eats 150 litres from the 4 Series' 370-litre boot space mind...

Other than the roof everything is as you were with a longer wheelbase, shorter overhangs and wider track than the 3 Series Convertible of old, all in the name of added dynamism.

Interior

Like the Coupé, the open-topped 4 Series features integrated retractable seat belts and electrically adjustable seats as standard. Also available from the options list are a pair of neck warmers that can be fitted to either the standard seats or the optional sport seats to keep the front occupants warm during a mid-winter topless blast.

Hidden behind the rear headrests are a pair of roll-over bars that can be deployed in less than 200ms should the sensors detect an impending roll.

Five different trim levels will be available: the BMW 4 Series Convertible, Sport, Modern, Luxury Line and M Sport, all featuring their own unique takes on what makes the perfect open top 4er.

Mechanicals

Save for some extra strengthening to account for the roof, most of the Convertible's oily bits are the same as the Coupé's. Complicated suspension setups (double joint spring strut up front and five-link rear) are said to deliver the dynamic abilities one would expect of a BMW, but with a level comfort suited to open top driving.

A range of TwinPower Turbo engines will also be carried over from the coupé with three powerplants offered at launch - two petrol and one diesel. The range will start with the 184hp 420d, which, in SE trim, will cost from £36,675. With a 0-62mph time of 8.2 seconds and fuel economy of 58.9mpg, this version is likely to be more popular with fleet buyers especially with its emissions of just 127g/km when the eight-speed automatic transmission is fitted.

For lovers of petrol the 245hp 428i returns a reasonable 42.8mpg and 154g/km, but can hit the benchmark 62mph time almost two seconds quicker than its diesel powered brother. Prices for that model start from £39,515 for an SE specification car.

Until the arrival of the M4 the performance powerhouse is the 435i. Its 306hp and 400Nm of torque results in a 5.5-second 0-62mph time - almost a second quicker than the 428i - but the penalty is fuel economy of 37.7mpg and emissions as high as 190g/km. The high powered model also eschews SE spec and skips straight to Luxury, resulting in a £44,970 asking price.

All models will come equipped with a six-speed manual transmission as standard but many owners are expected to opt for the eight-speed automatic.

Anything else?

Standard equipment will mirror that of the 4 Series Coupé and include Xenon headlights, heated electric front seats and front and rear parking sensors on all models. There will be a number of high tech optional extras available including BMW Connected Drive, the latest Navigation System Professional, Driving Assistant Plus and a high resolution Heads Up Display.

Paul Healy - 13 Oct 2013