How green hybrid tech is making AMGs faster

Published: 08 May 2018

► The tech powering AMG 53 cars
► Explaining EQ Boost and more
► Plus the new mild hybrid system 

Think of the Merc-AMG CLS53 four-door coupe and E53 Coupe and Cabriolet as the new ‘starter’ series for AMG’s larger cars, a little like the C-Class’s 43 range – but packing far more tech.

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The 53s feature Merc’s latest generation of straight-six mild hybrid powertrains, with 48-volt electrical architecture, an electric compressor in tandem with a conventional turbo, and a hefty electric power boost under acceleration.

The powertrain also features on other non-AMG Mercs including the CLS450. Here’s how it all works.

Mercedes-AMG CLS 53: now with EQ Boost and mild hybrid set-up

1) The ingredients of AMG’s 53 engine tech

The CLS53’s engine is a 3.0-litre straight-six with an exhaust-driven turbo plus an auxiliary electric compressor.

The key new element is EQ Boost, Merc’s name for an integrated starter- generator (ISG), which combines starter motor and generator in one powerful electric motor, housed between the engine and transmission. 

It helps provide extra go under hard acceleration (a boost of as much as 22bhp and 184lb ft), with energy recuperation for the battery, and with cold starts. It also enables gliding, where the engine drops temporarily out of the equation to help save fuel. 

Already in the S-Class, and soon in other Mercs too, the CLS53 has a 48-volt power supply as well as a conventional 12-volt system. It’s used for the boost function, energy recovery, and starting off and manoeuvring in electric mode.  

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Integrated starter generator built into straight six: the new AMG 53 engine tech in action

2) The sensible gains

Since the 48-volt system can also power the water and air-con pumps, it eliminates the need for a belt drive at the front of the engine, which reduces the overall length and creates space for exhaust gas after-treatment ancillaries. 

Although the 48-volt system has four times the power of a conventional 12-volt set-up, it requires only a quarter of the current, so the wiring can be thinner and lighter. The old-school 12-volt supply (which comes from the new network via a DC/DC converter) looks after the lights, instruments and control units.  

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3) The fun gains: it’s faster!

Never mind all that efficiency. This is an AMG model, so performance is top of the agenda.

With EQ Boost working its magic, the engine hits peak torque within two seconds under full throttle. The 2999cc straight-six packs 429bhp and 384lb ft by itself, without the 22bhp/184lb ft electric boost in play. 

The electric auxiliary compressor can build up a high charge pressure almost instantly, thus providing torque for acceleration until the conventional turbocharger can chime in, vanquishing the dreaded turbo lag. 

This, of course, is just the start for hybridised AMGs. The 48-volt on-board power supply is cheaper than plug-in hybrid technology, and Mercedes says it will be used widely across other engines and throughout other models in the regular and AMG line-ups. 

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By James Taylor

CAR's deputy features editor, occasional racer