Currently reading: Facelifted Mercedes S-Class to get new 48V mild hybrid tech
The implementation of a 48V system will introduce mild hybridisation across most of the brand's range, starting with the updated S-Class next year

Mercedes-Benz is poised to launch a major electrification onslaught with a switch to 48V systems that will allow the installation of mild hybrid assistance on almost its entire range over the next few years.

The first application will be a new M256-designated straight six petrol engine that will be introduced in next year’s facelift of the Mercedes-Benz S-Class and includes an electrical motor attached directly to the crankshaft. This can act as both an alternator and a starter – allowing the engine to fire up in just a fraction of a second – but it will also be able to add assistance and harvest electricity through regenerative braking.

This new straight six will progressively replace V6 engines throughout the Mercedes range. Although we have no statistics about the petrol engine yet, we’re told the electric motor can add up to 19bhp of assistance and harvest up to 20bhp during regeneration, delivering immediate economy gains of between 10% and 15%.

Unlike Mercedes’s high-voltage hybrid systems, there is no way of disconnecting the motor from the engine, so it can’t operate under electric-only power, but the relatively small capacity of the 0.9kWh 48V battery effectively rules this out anyway.

It seems likely that cars fitted with this electrical assistance system won’t carry hybrid branding, although Mercedes has confirmed the 48V set-up will in effect replace all of its non-plug- in hybrids.

The new six-cylinder petrol engine is based on the same architecture as the OM654 four-cylinder diesel that made its debut in the new Mercedes-Benz E-Class. Mercedes driveline engineering boss Jürgen Schenk said it will be joined by a diesel equivalent using the same integrated starter/generator later.

A four-cylinder petrol version with a less advanced belt-driven starter/generator will also be launched next year. That will mean all Mercedes cars using longitudinally mounted engines will have some form of mild hybrid assistance shortly afterwards.

Development of more powerful hybrid systems is also continuing. Mercedes will launch a 350 e version of the GLE Coupé, which will use the same underpinnings as the E 350 e. In addition, the S 500 hybrid is set to get a new battery pack next year. This increases capacity from 8.7kWh to 13.5kWh while retaining the same dimensions and 120kg weight and it will increase electric-only range to around 30 miles.

Jochen Strenkert, Mercedes’ head of plug-in hybrid powertrains, said it’s likely the same battery pack will be used to create a plug-in version of the diesel-powered S 300 hybrid.

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Mike Duff

Mike Duff
Title: Contributing editor

Mike has been writing about cars for more than 25 years, having defected from radio journalism to follow his passion. He has been a contributor to Autocar since 2004, and is a former editor of the Autocar website. 

Mike joined Autocar full-time in 2007, first as features editor before taking the reins at Being in charge of the video strategy at the time saw him create our long running “will it drift?” series. For which he apologies.

He specialises in adventurous drive stories, many in unlikely places. He once drove to Serbia to visit the Zastava factory, took a £1500 Mercedes W124 E-Class to Berlin to meet some of its taxi siblings and did Scotland’s North Coast 500 in a Porsche Boxster during a winter storm. He also seems to be a hypercar magnet, having driven such exotics as the Koenigsegg One:1, Lamborghini SCV12, Lotus Evija and Pagani Huayra R.

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jtaza 22 July 2016


So do I have this straight that EVERY 6 & 4 cylinder vehicle thats NOT a hybrid will eventually have the 48V / 12V mild hybrid architecture? Just trying to wrap my arms aroud how many models this implies...
Bob Cholmondeley 11 June 2016

Given the way German

Given the way German manufacturers reliability seems to suffering these days, do we really need further drivetrain complexity? If you want a hybrid, buy Japanese, then you know it will work.
TheSaintmobile 11 June 2016

I hope the V8s remain. I can

I hope the V8s remain. I can do with a Merc with 6 & V8. never with a 4.