Lambo Blogging: 2019 Mercedes-Benz CLS Prototype Review: The Return of Mercedes’ Swoopy Coupe

SAN FRANCISCO – Invoking the description “cultured sporty” for its redesigned 2019 CLS four-door coupe, Mercedes-Benz will revive its swoopy styling while delivering an array of new engines.

Fans of the original CLS will be gratified to see the return of one long sweep of side sheetmetal, ditching the ungainly rear haunches from the second generation. Sadly, the crisp character line of the first-gen CLS does not make a return, with Mercedes instead providing more of a muscular shoulder. The rear deck has a bit of a pouty lip at the trunklid edge, which might be a polarizing touch.

The CLS will be a nimble combination of unique parts and platform sharing. It will ride on the MRA platform shared with the E-Class and carry the same wheelbase and axles (although the CLS and E-Class have different overall lengths and tracks, giving the CLS the appearance of its 19-inch wheels being pushed farther to the corners; Mercedes declined to provide specific dimensions for the CLS). Meanwhile, the engines and electronics will be shared with the S-Class. The seats and most of the interior will be unique to the CLS.

Despite its sleek appearance, the CLS is actually less slippery than the E-Class—with a 0.26 cD compared to 0.23 for the stockier-looking sedan. Why? Much had to do with the keeping the rear axle on the ground at higher speeds without adding a spoiler, which would ruin the line of the car. So a lot of aerodynamic work happens underneath the CLS. You don’t see it, but the wind does.

Unfortunately, due to our different bumper-testing regulations, the U.S. gets a different rear bumper—one that loses the cool flushness that every other market gets. “Why ruin it for everyone else?” CLS chief engineer Michael Kelz said.

The CLS450 will come with the 3.0-liter turbocharged, supercharged, and hybridized M256 inline-six that generates 367 hp and 369 lb-ft, utters a great throaty snarl, and reaches 62 mph in 5.0 seconds. Given those output numbers, it seems the CLS’ engine is slightly detuned from the version that appears in the S-Class. A forthcoming AMG version will have 430 hp and shave 0.2 second off the 0–62 time.

Kelz says the inline-six “splits the hot and cool sides” based on exhaust routing—placing the catalytic converter, 48-volt assembly and 12-volt converter, the twin-scroll turbocharger, and the rest of the exhaust system on the driver’s right while the electric supercharger (or e-turbo as they often call it) resides on the driver’s left. The 12-volt battery is now carried in the back of the car.

Europe will also get a CLS350 with a completely new 300-hp, 295-lb-ft 2.0-liter four-cylinder code-named M264—although Mercedes engineers quietly note that the four-banger could migrate to America, as well.

Six- and four-cylinder diesel variants will also be sold in Europe; the OM656 inline-six generates 286 hp and 443 lb-ft of torque, and a four-cylinder oil-burner will create 245 hp and 369 lb-ft of twist.

The CLS will come with a choice of three suspensions: a standard steel suspension, an adaptive steel suspension (the sportiest of the three), and a multichamber air suspension.

For this specialized version of Mercedes’ Air Body Control, engineers decided that air springs were too floaty for sporty driving and used the E-Class’ multichamber system rather than the single-chamber of the S-Class. Despite being similar systems, there are differences in their respective applications—the E-Class responds slower but is also plusher, and the CLS is more about higher frequency and immediate response, said Hubert Schneider, head of testing for the E-Class, CLS, and GLC.

The result: flat cornering, even in Comfort mode. Rebound damping is exquisite even with the standard steel springs—as we found during a half-day drive from San Francisco down the Northern California coast and foothills. During a challenging chicane, the CLS squats solidly during the weight transfer.

As per traditional Mercedes drive modes, Eco, Comfort, and Sport will be available—defaulting to Comfort with each cycle of the ignition. However, in some city driving, Comfort might be more fuel-efficient—Eco is meant more for long-haul “sailing.” An available Intelligent Eco setting coordinates your destination with instant navigation and radar data for maximum fuel efficiency. When in sailing mode, the engine will be off—not idling—and will turn back on if engine braking is needed.

How does it do this? A 48-volt integrated starter generator, shared with the S-Class, can handle advanced stop/start, coasting, and electric boost. Also, the air-conditioning compressor is electrically driven, meaning the stop/start system can keep the engine off for longer periods. When sitting in heat-soak conditions with the engine off and the air conditioning on automatic, the electric compressor had no problems keeping the cabin cool.

Inside, the CLS will carry a fully digital instrument panel shared with the S-Class. Cool cyclone-looking air vents are arrayed in a 1-4-1 pattern across the console. (The E-Class also gets them for 2019 model year.) The inlays in the dash and door panels might look like carbon fiber, but they are a woven steel matrix. Each vent and panel has surrounding illumination in a selectable choice of 64 ambient colors that will make the Pantone deities smile.

Leather seats hold occupants firmly in place but are comfortable for longer drives. LED headlamps can cast their light nearly a half mile ahead. Two-pane acoustic glass from supplier AGC Automotive lends to the quietness of a bank vault—generating almost reverse air pressure on occupants’ tympanic membranes, yet just enough of the thrilling I-6’s note comes through to remind you that this is a performance car.

The form-over-function design does result in back-seat compromises, including tight headroom, splayed knees, and ingress and egress that require craning your neck to avoid a head versus headliner collision. The rear-seat headrests are small pads designed for safety more than comfort—but larger headrests would mean an even smaller visual area out the back.

The CLS goes on sale in Germany in March or April; the U.S. gets its first units in July. The U.S. market will initially get all-wheel-drive versions and then slowly integrate rear-drive versions into the dealer fleet.