2019 Mercedes-Benz CLS450

2019 Mercedes-Benz CLS450 test drive: Benz gets back inline with straight-six

The 2019 Mercedes-Benz CLS 450 is an all-new car, but it marks the return to the brand of an old kind of engine: The inline-6.

Once a mainstay of the luxury car segment, thanks to its smooth-running operation of their well-balanced cylinder firing order, you've only been available to get one in BMWs and big diesel trucks in recent years.

Mercedes hasn’t offered an inline-6 since 1999, having transitioned to V6s for a variety of manufacturing and packaging reasons, but has once again succumbed to the layout’s allure.

It’s not like its V6s are rough riders, but another one of the straight-6 advantages is the fact that they need half as many of some parts, like camshafts and turbochargers.

The blower strapped onto the 3.0-liter in the CLS450 is a big one, which means it’s relatively slow to spool up. That typically leads to the dreaded turbo lag during acceleration, but this powerplant adds a high tech twist…literally.

(Mercedes-Benz)

The 362 hp, 369 lb-ft engine is also fitted with an electric motor that not only acts as a starter/alternator to enable fuel-saving stop/start capability, but also provides a boost of 21 hp and 148 lb-ft that’s available as soon as you step on the accelerator. This fills in the gap while the turbo gets to work and, fed through the 9-speed transmission and all-wheel-drive system in the example I tested, it didn’t leave me wanting for the V8 from last year’s CLS 550 that it effectively replaces one bit.

Straight-sixes will be finding their way under the hoods of many Mercedes in the coming years (at least until electric motors take over), but the CLS450 was the perfect place to start. The third-generation of the original “four-door coupe” replaces the bulky exterior design of the last version with sleek lines that make the body look like it’s pulled as tightly as a drumhead and are more than worth trading for the tight rear headroom, at least compared to the E-Class sedan that the CLS is related to.

(Mercedes-Benz)

The CLS450 gets all of the good stuff from the E-Class, too. This includes its opulent, LED-enhanced interior, dreamy air-suspension, twin foot-wide digital displays and excellent semi-autonomous driver aids, which can self-steer the car in a lane for short periods and even change lanes with a flick of the turn signal stalk, if the car sees that the coast is clear.

Pricing for the CLS450 hasn’t been announced, but the CLS550 started at $76,145.