Mercedes-AMG CLS53 to debut 320kW inline six hybrid powertrain

MERCEDES-AMG is poised to roll out a juiced-up performance version of Benz’s all-new inline six-cylinder petrol engine and introduce a ‘53’ model grade to replace its short-lived, V6-engined ’43’ models.

The all-new third-gen CLS will be first to wear the 53 badge. The CLS53 is expected to be unveiled in March next year featuring the hotter six with hybrid electrical assistance, followed by a local arrival in the third quarter of 2018.

Speaking to Wheels at the launch of the E-Class Cabriolet, a source within the company revealed the nomenclature and said AMG’s warmed-up version of the turbocharged M256 3.0-litre inline engine will generate a sizeable 320kW on its own, with a 50kW boost from an electric motor available when extra shove is required.

Those outputs represent a considerable gain over the current E43’s 295kW peak power, and it awkwardly close to the C63 S’s 375kW 4.0-litre twin-turbo V8.

E53 coupe and cabriolet variants will follow, and an S-Class variant is also part of the product plan. It’s not yet clear how long punters will need to wait for a C53 version, but it’s likely a case of ‘when’, not ‘if’.

Given AMG’s massive model growth in recent years, expect the inline six to eventually roll out across all of Benz’s longitudinally engined offerings - including the GLC, GLE and GLS SUV ranges. It seems likely smaller models may forgo the hybrid hardware to keep cost down and increase separation between the ‘53 and even more powerful ‘63 variants.

The higher 53 numeric isn’t just a marketing move to elevate it above the likes of the CLA45 and A45 in the AMG hierarchy, but is also a reflection of the new six’s extra performance over the 3.0-litre biturbo V6 that it will replace.

Benz’s boosted straight six is dubbed M256 in non-AMG form, and will debut in the revamped S-Class later this year.

According to our source, AMG has no plans to transplant the dragon-slaying E63’s 450kW twin-turbo V8 powerplant into the snout of Benz’s just-launched E-Class cabriolet. The new turbocharged inline six will feature in the big convertible as the only AMG variant for that model.

“For the E-Class cabrio, we’ll only bring a six-cylinder AMG version. No eight-cylinder, no 63.” they confirmed.

Given the new powertrain’s V8-rivalling grunt the six is hardly a consolation prize.

It’s not yet clear precisely how the 50kW hybrid system hinted at for the CLS 53 and E53 will be integrated, but Wheels understands it won’t come with a plug-in charging system due to packaging constraints - at least for the cabrio. Limited space for batteries means that for the E53 Cabriolet won’t be able to be driven on electric power alone - at least not for any meaningful distance.

The next AMG A45’s 2.0-litre four-cylinder engine will share architecture with the 3.0-litre six and also employ an electric power-adder in the form of a lag-reducing electric turbocharger (or ‘electrochargers’). An electric compressor spooling up when the engine is operating at low revs promises a more linear power delivery than a conventional turbo setup.

AMG products command a significant chunk of Mercedes Australia’s sales pie, with the company on track to deliver around 6000 cars from AMG’s ever-growing model line-up before the end of 2017.

Much of that growth can be attributed to the arrival of the mid-strength AMG ‘43 models. In the C-Class’ case, the C43 outsold its more powerful C63 sibling for two months this year, however those sales were in addition to what the C63 model would normally sell. Latent demand for more approachable – and affordable – AMGs clearly hasn’t stepped on the toes of its V8 flagships.