What's all this about?

Mercedes-AMG is expanding its portfolio with a new '53' model designation. It's introducing a whole new engine type - an inline-six petrol with electric augmentation - and also marks the world debut of the first proper performance version of the third-generation CLS.

Erm... what now?

OK, so we have the Mercedes-AMG CLS 53, E 53 Coupe and E 53 Cabriolet. That covers off the first hot CLS and the introduction of the 53-badged family of AMGs. These sit between the pre-existing 43 models (with a 3.0-litre V6 twin-turbo and between 367hp and 401hp) and the flagship AMG 63 (4.0-litre V8 twin-turbo, between 476hp and 612hp). And this '53' nomenclature is Mercedes-AMG's first step on the road to hybridisation.

OK, I'm intrigued - can you tell me some more?

So, for anything badged 53, we've still got a 3.0-litre twin-turbo six-cylinder petrol engine, but the cylinders are no longer in a V - instead it's a 'straight' six, with the pistons all line astern. And one of the two turbos is an electrically-powered compressor that negates turbo lag, before a bigger, conventional exhaust-driven turbo kicks in higher up the rev counter. It's similar to the system seen in the Audi SQ7, so Mercedes-AMG's set-up requires a 48-volt electrical system for all the cleverness. It also features an EQ Boost starter-alternator that can momentarily dump an extra 22hp and 250Nm on top of the inline-six's base stats of 435hp and 520Nm.

Wow, fancy stuff, this. What does it mean for performance?

Well, all three 53s are suitably brisk, as they also feature the AMG Speedshift TCT 9G gearbox and AMG Performance 4MATIC+ all-wheel drive, which helps negate kerb weights which are all approaching two tonnes. The E 53 Coupe is the quickest, managing 0-62mph in 4.4 seconds, while the CLS 53 and E 53 Cabriolet take 4.5 seconds. All three can do an electronically limited 155mph, although the restrictor can be lifted to 168mph as part of the AMG Driver's Package. Fuel economy is 33.6mpg with 200g/km of CO₂ emissions on the CLS 53 and E 53 Coupe, with the E 53 Cabriolet only slightly worse, at 33.2mpg and 201g/km.

And I take it they all look like the current AMG line-up?

You are correct. Inspired by the V8 models, the 53s have twin-blade radiator grilles, an 'A-wing' front apron, AMG-specific side skirts and a rear bumper that houses a diffuser and round exhaust pipes in high-gloss chrome. Inside, there's the option to have the Widescreen Cockpit twin 12.3-inch TFT displays for the infotainment and instrument cluster, while there's a new AMG Performance steering wheel offered as standard. Big wheels are also a given, while the CLS 53 has its mirrors mounted on its doors, rather like the AMG GT sports car at the top of the AMG range.

Are these available to order now?

Having been shown at the Detroit Motor Show, the CLS 53 and E 53 twins should hit the market almost immediately. And, at this point, we'll hand over to Tobias Moers, the chairman of Mercedes-AMG, who said: "With the new 53-series models, we are extending our portfolio in a first step towards a hybridised future with a leading-edge combination of sporty design, performance and efficiency. The basis for this is a contemporary drive configuration in the form of a six-cylinder inline engine with electric auxiliary compressor, EQ Boost starter-alternator and 48V onboard electrical system. The very spontaneous response to accelerator pedal input, the precision and the design focusing on driving dynamics are hallmark features of AMG. As such we are providing an additional lifestyle-oriented customer group with a further attractive offering from Affalterbach."