The first-ever Mercedes-Benz S-class convertible has broken cover in the form of a test mule prior to its launch in 2014.

Based on the CL-replacing next-generation S-class coupé, the new Mercedes will open up a fresh niche for large luxury 2+2 soft-tops, occupying territory close to the Bentley Continental GTC, where usual rivals BMW and Audi have yet to tread.

The well camouflaged mule fails to disguise the heavily raked windscreen (shared with the S-class coupé) and the large rear quarterlight window, which gives an indication that the rear cabin will be relatively generous for a soft-top.

Compared with the E-class convertible, the S-class will have a roomier, higher-quality cabin, which will be part of its appeal to owners who want the space to carry a pair of adult passengers in open-top luxury.

Although the mule gives away a little of the convertible’s details, it does reveal a large, sweeping roofline, with the canvas hood tucked away under a fake hard-top roof. The two-door body style that sources have indicated will feature in production is also obvious in our photographs.

Mercedes has previously floated the idea of a luxury soft-top in the shape of the 2006 Ocean Drive concept, although that experimented with four-door styling.

A key feature of the new S-class is the classy, near-Bentley-quality interior. Scoop pictures of the cabin have previously revealed a fully digital dashboard with a four-dial instrument pack, paired with a widescreen sat-nav/multimedia system set in matching rectangular binnacles.

Extra luxury is added by a swathe of wood trim across the cockpit, punctuated by ‘eyeball’ air vents fashioned from metal, which look like they’ve been lifted straight out of a Bentley parts bin.

Under the skin, the S-class convertible will be packed with high-end technology, much of it focused on improving the car’s road manners and breaking new ground in safety.

Like the next-generation S-class saloon due next year, the convertible will feature ‘Magic Ride’ suspension, first revealed on the company’s F700 concept. It employs cameras that detect the road surface and adjust the air springs and dampers to suit the prevailing conditions. By working on each wheel individually, the system is said to be able to provide a constant ride height and eradicate cornering lean.

As on every generation of S-class, new safety technology will also be introduced. This is likely to include refinements to Mercedes’ convertible rollover system.

A ‘Braking Bag’ under the front axle, activated during the last moments of an emergency stop, will provide extra retardation. The car is also expected to incorporate a new seatbelt-mounted airbag.