2017 Mercedes-Benz E-Class Cabriolet - details and first prototype ride

Autocar can also confirm AMG is developing a new E 50 Cabriolet 4Matic powered by a reworked version of Mercedes' new twin-turbocharged 3.0-litre in-line six-cylinder petrol engine and an integrated start motor with an electronic boosting function, developing in the region of 450bhp.

The E-Class Cabriolet is larger than its predecessor. Official measurements are yet to be made official, though Früh indicates they match the 4826mm length, 1860mm width and 1430mm height of the E-Class Coupé. This makes it 128mm longer, 74mm wider and 32mm higher than the previous E-Class Cabriolet.

The car's folding roof, engineered by Austrian specialist Magna, draws heavily on the design of the smaller C-Class Cabriolet's. The fully automatic structure folds in a familiar scissor action and stows in its own dedicated area underneath a plastic tonneau cover behind the driver. Putting the roof up or down takes just 20sec.

The construction of the three-layer hood, which can be operated while driving at speeds up to 31mph, is described by Früh as being considerably more sophisticated that that of the old E-Class Cabriolet, in terms of structure and materials. “We have spent a lot of time and effort perfecting the inherent strength and acoustic qualities, both virtually on the computer and in real-world testing,” he says.

Mercedes-Benz claims a boot capacity of 360 litres with the roof up, meaning the new car has 30 litres less room than its predecessor and, despite a longer wheelbase and a larger body, just 5 litres more than the smaller C-Class Cabriolet. However, the E-Class Cabriolet's rear seats can be folded down for more storage space. 

Occupant protection, meanwhile, is taken care of by a stronger windscreen, which features reinforced anchoring points and high-strength steel buttressed frame. There are also two substantial beams integrated into the rear bulkhead, which fire through a plastic trim panel should sensors detect the car is going to roll over, the metal structures are. There are also high-strength steel strengthening elements within the car's sills and rear bulkhead. 

The E-Class Cabriolet has the same interior as the E-Class Coupé, with a new dashboard, instruments and controls. An optional 12.3in digital instrument display and multifunction steering wheel featuring touch sensitive pads as part of the latest Comand APS NTG 5 infotainment system is also available. Passenger room is better all-round, but most notably in the rear, which has greater leg and shoulder room than before.

Impressions from the passenger seat

To find out what the new drop-top E-Class is like, we traveled to Arizona, US, where Mercedes-Benz is conducting the car's final validation tests ahead of its planned world debut at the Geneva motor show in early March. 

A stable climate, plenty of coarse-chip bitumen surfaces and abundant gravel roads with plenty of dust make for perfect testing conditions. That it's also home to its alliance partner Nissan’s vast technical centre located on the outskirts of Phoenix, where Mercedes-Benz now conducts a good deal of new model development testing, is also key to why this location was chosen.

There are two cars on hand, lightly disguised hand-built prototypes that have already been put through an arduous two-week testing program. They’re here for some final calibration and the sign-off of 'project A238', as the model is codenamed, before the start of production at Mercedes' Bremen factory in Germany and a UK launch later this year.  

The prototype we’re riding in is the four-wheel-drive E 200 4Matic. It has the latest version of Mercedes' M274 four-cylinder turbocharged 2.0-litre petrol engine, which, as in the E 200 Coupé, makes 181bhp. 

The other car is a rear-wheel-drive E 300 d. While Früh is tight-lipped on the exact details of its engine, it's believed to be an uprated version of the new OM654 four-cylinder turbocharged 2.0-litre diesel, with more than 240bhp.   

Whether these two engines will be offered in the UK is yet to be confirmed. 

When we hit public roads after a brief outing on Nissan’s test track, there’s imbibing smoothness, if not great muscularity, to the E 200 Cabriolet.

One of its key strengths is the impressive integration of its engine and gearbox, and the resulting refinement.

And despite the added weight brought on by the additional stiffness, the car feels tremendously composed, with barely any scuttle shake, even on corrugated surfaces. It’s best work is done at a constant throttle cruise at typical motorway speeds, although it also proves quite adept on more challenging roads. There’s a small amount of body lean when you corner hard in Sport mode, but otherwise it's surprisingly agile, with progressive and predictable handling when pushed hard.