Mercedes unveils strong, frugal diesel

MERCEDES-BENZ has announced that a new generation of four-cylinder diesel engines – claimed to “outstrip all previous benchmarks for performance, torque, emission properties and, most notably fuel economy in their segment” – will be introduced across a number of model lines, beginning with the C-class later this year.

Compared to the current 220 CDI 125kW/400Nm 2148cc oil-burner, the range-topping Euro V-compliant 250 CDI 2143cc twin-turbocharged diesel delivers 150kW and 500Nm but is claimed to burn “substantially less” fuel and, as a consequence, reduce emissions by as much as 13 per cent.

When installed in the C-class, an updated version of which is due in Australia next year, the 250 CDI returns 5.4L/100km – 0.5 litres less than the current 220 CDI – and 143g/km of CO2. It can also accelerate from 0-100km/h in 7.7 seconds, and overtake from 60-100km/h in 9.4 seconds.

Codenamed OM651 and marking the fourth generation of Mercedes common-rail diesels (now with 2000 bar maximum rail pressure, up 400 bar), the new powerplant can be installed both lengthways and crossways and is envisaged for AWD as well as rear-drive applications.

It can be supplemented by the BlueTec emissions control system and is also earmarked for use in forthcoming diesel-electric hybrid applications.

Two other variants of the diesel engine, all of which now have a compression ratio of 16.2:1 (down from 17.5:1) are planned for use in passenger cars: an updated 220 CDI (still with 125kW/400Nm) and a 200 CDI single-turbo unit producing 100kW/330Nm.

“This takes our new four-cylinder unit into a realm which has so far been the preserve of three-litre six-cylinder diesel or large V8 petrol engines – all combined with exemplary fuel economy," said Mercedes-Benz R&D chief Thomas Weber.