2018 Mercedes-Benz E-class Cabriolet

The sun lies low on the desert horizon, the trees and cactuses are throwing long shadows, and the landscape is doused with warm light. In less than 20 seconds, the softtop disappears behind the rear seats, and the engine—barely perceptible—springs to life. The beginning of a relaxed and indulgent drive into the Sonoran Desert?

Hardly. This trip requires the utmost concentration: We are riding along on one of the final engineering drives for the Mercedes-Benz E-class convertible, a model Daimler calls the cabriolet. At the wheel is Christian Früh, development chief for the coupe and convertible C- and E-class models. In another of several prototypes on this drive, the pilot is Peter Kolb, testing chief for the new models. One car is a Europe-spec E200, with a 181-hp turbocharged inline-four making even less power than the 241-horsepower four found in the base U.S. sedan, the E300. Another car has a four-cylinder turbo-diesel that’s so quiet you would be forgiven if you confused it with a six, but don’t expect to see that at U.S. dealerships, either.

In the U.S., the convertible will be an E400, like the E-class coupe, powered by a twin-turbo V-6 gasoline engine. In the coupe it’s rated at 329 horsepower and 354 lb-ft of torque, and those figures are likely to be the same in the softtop version. Note that the day of V-8–powered E-class convertibles appears to be past, our fond memories of the E550 cabrio notwithstanding. Although the E63 sedan uses AMG’s thundering 4.0-liter V-8, the AMG version of this new cabriolet will most likely be an E50 powered by a turbocharged inline-six. Don’t look for that one in the first couple of model years, though. Every E-class convertible will come with Daimler’s own nine-speed conventional automatic. If Mercedes follows its usual practice of late, it will offer its 4MATIC all-wheel-drive system as an alternative to the standard rear-drive configuration.

This test drive is supposed to deliver the finishing touches on these most upscale derivatives of the E-class, the mid-size line that more or less defines Mercedes-Benz to a large portion of the general public. Many thousands of miles of development work preceded our ridealong. Unlike the previous E-class convertible that was actually built on C-class architecture, the new model is E-class from the ground up, with a heavily modified structure adding braces under the engine and below the trunk to make up for the rigidity lost without a steel roof. Using the E-class platform makes it quite a bit larger than the outgoing model, which was the brand’s only four-seat convertible when introduced. The new one will share showroom space with four-seat ragtop versions of both the smaller C- and larger S-class.

While the open-top C-class looks compact and muscular, the E-class cabriolet’s straight, unbroken lines give it a more elegant, almost Italianesque aspect. There is quite a bit more rear-seat space than in either the preceding-generation E- or today’s C-class cabrio, so even extended journeys should pose no problem for rear-seat occupants. When the multilayer roof is raised, it isolates the interior so well that the difference from the coupe is barely perceptible.

The new car’s dashboard transfers directly from the sedan with one important change: The cabriolet, like the E coupe, comes with metallic air vents resembling jet turbines, which aren’t used in the sedan. Further differentiation stems from distinct leather colors and light-colored open-pore wood décor not offered in the sedan. Part of the point of this test drive in Arizona is finding out how well these new materials hold up when subjected to the Southwestern climate.

We weren’t allowed behind the wheel at all, but judging from our passenger-seat vantage, the cabrio chassis seems remarkably stiff and responsive to Früh’s steering inputs. The ride height is lower than the sedan’s by 0.6 inch. Agility is not a traditional strength of the mid-size Mercedes-Benz, but our impression is that the new cabriolet will be every bit as responsive as the sedan, although its primary mission is to be more comfortable than the softtop C-class.

Expect to see the E-class cabriolet revealed at the Geneva auto show in March and in dealerships this summer. The E-class, it seems to us, could be a relaxed and elegant choice among luxury droptops. We look forward to getting behind the wheel in a few months.