The 2019 Mercedes CLS adds efficiency to high performance

Along route C-59, some 50 kilometres outside of the Spanish port city of Barcelona, the unthinkable happened.

As we cruised along at 120 kilometres an hour in a brand-new Mercedes CLS coupe, the engine stopped running.

Really, Mercedes? Before alarm took root, we quickly realized the car was still going, courtesy of the "sailing" feature in the 2019 version.

To save fuel, the six-cylinder engine shuts down when it's not under load. When the load resumes, the engine seamlessly kicks back in, with only the movement of the tachometer needle to show that anything has happened.

The new CLS, the third generation of the so-called "four-door coupe" since its debut in 2004, is all about bringing greater efficiency to its well-earned reputation for performance. Hence, this CLS has a cleaner, more aerodynamic shape than its predecessor, giving it a low drag coefficient of 0.26. And it has a mild, sort-of hybrid system, which Mercedes calls EQ Boost – there to boost power more than economy. A starter-generator placed between the engine and transmission is linked to a 48-volt lithium ion battery (there is a 12-volt battery, as well, for normal stuff). It offers a brief boost of power and torque during acceleration and helps keep the car moving when it is in sailing mode.

Gorden Wagener, chief design officer at Daimler AG, notes the new CLS took the sharp edges off the shape of the vehicle, adding smooth curves reminiscent of a smartphone.

"The third-generation CLS brought the car back to its original DNA," he said, a tacit admission, perhaps, that Generation 2 was a trifle sedate in appearance. In fact, the appearance of the Gen 2 was about as exciting as vanilla ice cream at a Hershey's convention. Wagener said the new CLS's "predator face" front end, with its diamond-grid grill and triangular headlamps, is designed to provide a more aggressive look.

Inside, the loungey interior is clean, uncluttered and as dignified as a luxury sedan should be. Yet a 64-colour ambient lighting system, massaging air-cooled seats and hypnotic music straight out of a health spa enables the driver to get so mellow, he might need to rely on the standard lane-departure alert just to stay on the road.

The illuminated air vents that glow blue when cooling and red when heating link the visual and tactile. And one of the most beautiful iterations of the interior is found in the limited Edition 1; its copper art tints throughout the cabin are an aesthetic gem.

Let's be honest: This two-headed monster isn't just about fuel thrift and comfort. The CLS's five driving modes cross the spectrum from hyper-miler eco right up to road-racing Sport+, which boosts the revs, tightens the suspension and steering, and spools up the turbo for a law-bending assault on twisty two-lane roads.

Mercedes aficionados will note that this is the first CLS to be equipped with an inline 3.0-litre six-cylinder engine, rather than the previous generation's V-8. Peter Kolb, head of overall vehicle testing for the CLS, said the smaller engine is in response to the relentless demand for greater fuel efficiency. There is a diesel version of the six-cylinder (and a four-cylinder on the way), but neither is scheduled for the Canadian market. Although Mercedes did not provide weight figures, this car is very close to the previous model's two tonnes.

The horsepower rating in the sporty AMG drops from 577 hp in the 2018 to 429 hp in the 2019, but the EQ boost technology gives this Popeye its spinach – adding 184 lb-ft of torque to the engine's own 384 lb-ft. All those numbers simply mean that when you punch down the throttle, this car will pin you to your seat like the washing machine pastes your clothes to the side in the spin cycle.

Mercedes chose the burnt sienna hillsides around Barcelona, with the area's combination of gently sweeping motorways and winding two-lane roads, to demonstrate the CLS's capabilities. Both the base CLS and the steroid-injected AMG 53 were able to transition from a comfortable highway cruiser to an aggressive back-road runner with a simple flip of the driving mode.

The difference was most dramatic in the AMG. The instant response of the EQ electric booster accelerated the car without the typical split-second delay that bedevils most turbo-boosted cars. You feel like the stone in a slingshot. The surge of power is conveyed through the 4-MATIC transmission with its rapid-fire shifting and all-wheel drive. At speed, AMG's ride-control air suspension and continuously variable damping takes the sharpest of curves with confidence and stability. It feels as good as it looks.

Under acceleration, the engine's truculent growl crept into the quiet cabin, followed by a joyful "pop-pop" when your foot comes off the gas. Cumulatively, the experience lets you channel your inner Michael Schumacher.

The new CLS looks better and gets better fuel economy than its predecessor. But at a price point approaching six figures for even the base model on this German-built car, economy is a relative term – if you can afford to buy it, you're not doing so to save money on fuel. It also faces stiff competition from other German auto makers, such as BMW and Audi, which is reported to be close to launching its new A8, with coasting function and mild-hybrid format similar to the CLS's.

You could wait to see how the competition stacks up, but the 2019 CLS will arrive in Canada late summer. Start saving.

Tech Specs

• Base price/as tested: Not released, but expected to be just slightly more than the 2018 base price of $93,500 (CLS) and $130,400 (AMG 53), plus destination and delivery
• Engine (standard): 3.0-litre, six-cylinder twin turbo
• Horsepower (CLS/AMG 53): 362 hp, plus 21 hp (EQ Boost) / 429 hp, plus 21 hp (EQ Boost)
• Transmission (CLS/AMG 53): Nine-speed G-tronic automatic; Performance 4MATIC+ with fully variable torque distribution
• Fuel economy (CLS/ AMG 53) (litres/100 km): 10.5 city/5.4 highway; 11.6 city/7.2 highway
• Alternatives: Audi A7 Sportback, BMW 6 Series Gran Coupe

Looks

The clean side panels and aggressive shark-like front are set up with a subtle flip at the tail. It's the best-looking of the three generations of the CLS.

Interior

The continuous colour concept, combined with fine craftsmanship, gives the interior a lounge-like yet luxurious feel. Mood-setting colour lights and vents that glow red when heating and blue when cooling add a sense of fun.

Performance

The basic CLS 450 accelerates aggressively, stops even better and stays stable through tight turns. The 429-hp AMG turns this car into an authentic hot rod, when it's in Sport+ mode. The EQ boost system provides a jaw-dropping extra 184 lb-ft of torque in short bursts.

Technology

It has all the high-tech safety features you'd expect in a modern luxury automobile, plus a vast array of choices to personalize the performance and interior ambience.

Cargo

The CLS now seats five, including three slim-hipped passengers in the back, and provides a respectable amount of trunk space. For a road trip, it's ideal for two.

Verdict

9.0

Its handsome appearance, quiet cabin, thrifty fuel consumption and heart-stopping on-command power make for a memorable driving experience. You can alternate between hyper-miler and racer in the same road trip. But with a price that starts near six figures, this car will remain a dream for typical drivers.

You'll like this car if …

You just have to have the latest technology, love German engineering, have a need for speed, and don't fret about making the monthly mortgage payments.

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