Meet Merc's first all-alloy diesel

Mercedes-Benz has defied speculation of a crisis for passenger-car diesel engines by unveiling its all-new oil-burning engine range for the new-generation of the E-Class.

The all-new OM 654 engine series will be the first all-aluminium turbo-diesel to come from Mercedes-Benz and will be one of the key tools for the brand in meeting its 95g/km CO2 limit, scheduled to be introduced in Europe in 2020.

It will begin rolling the new engine family out with the E-Class in April this year (late 2016 in Australia) before fitting it to the C-Class and the bottom half of its SUV family, pre-fitting them with sub-95-gram technology before 2020 becomes a log-jam date.

The modular four-cylinder engine will also become an inline six-cylinder engine and has the potential to shrink down to become a three-cylinder engine for the A- and B-Class, though Benz refuses to rule out putting the smallest version of the motor into the C-Class.

It is pre-engineered to be used in transverse front-wheel drive, longitudinal rear-wheel drive and all-wheel drive applications, and is adaptable to fit with mild-hybrid and plug-in hybrid powertrains.

It will arrive first in the E 220d, with one key to its future in the Mercedes-Benz range being the decision to move its exhaust after-treatment technology onto the engine itself, rather than having to find space for it inside the car. All versions of the engine have two-stage exhaust gas recirculation.

The new powertrain, which replaces the 2.15-litre OM 651 diesel, pulls the capacity down from 2.15 litres to a neat 2.0 litres, shrinking its external dimensions as well while lowering fuel consumption by around 13 per cent.

It’s also a far lighter motor than the outgoing engine, lowering the mass from 202.8kg to 168.4kg, which should help deliver better handling and balance.

Its power has risen in E220d form from 125kW to 143kW, thanks to the adoption of some technology Mercedes had been reserving for its performance models.

“The new family of engines embodies over 80 years of Mercedes-Benz diesel know-how,” Daimler’s board member for Research and Development, Professor Doctor Thomas Weber said.

“The new premium diesels are more efficient and powerful, lighter and more compact – and they are designed to meet all future global emissions standards.

“In our opinion, the diesel engine is indispensible in trucks and cars if we want to further reduce the CO2 emissions from traffic.”

It uses the same Nanoslide cylinder bore technology as the Mercedes-AMG Formula 1 car, which came from its performance sedans originally. It couples this spray-on hard, smooth cylinder lining with new steel pistons and stepped combustion bowls, along with the fourth generation of Benz’s common-rail fuel-injection system.

Along with lifting power to 143kW at 3800rpm, the E 220d’s new motor brings 400Nm of torque, peaking from 1600 to 2400rpm and delivering a specific output of 72kW per litre.

It’s an undersquare motor, with a bore of 82mm and a stroke length of 92.3mm, creating a 1950cc displacement, with 154mm-long connecting rods.

It is capable of soaking up 205 bar of cylinder pressure and uses a 15.5:1 compression ratio in each of its 487.5cc cylinders, with each bore centre 90mm apart.

It saves weight by reducing the capacity and by simplifying the turbocharging down to a single stage.

It also uses plastic engine mounts, which are lighter than the current steel units, and Benz has moved the balancing shafts so they now sit on either side of the engine, rather than below it.