C220 CDI BlueEFFICIENCY with 170 hp/125kW and 400 Nm of torque rates 4.8 liters/100 km. Also new is the C250 CGI EFFICIENCY, a direct-injection gasoline/petrol engine with 204 hp and 310 Nm of torque that does 7.2 liters/100 km.

It's getting tougher and tougher to make an argument against diesels these days, as automakers continue to rapidly improve the performance and emissions ratings of their so called oil-burner engines.

But despite the advances European automakers have made with their diesel offerings, Mercedes seems to be inching ahead with their BlueEFFICIENCY label.

Case in point is the new C220 CDI BlueEFFICIENCY engine now available on the C-Class (with 170 hp/125kW and 400 Nm of torque). That 2.1 liter (2143cc) diesel achieves a fuel economy rating of 4.8 liters/100 km (58.85 UK mpg) - quite a leap from the 6.1 liters/100 km (46.31 UK mpg) of its previous, non-BlueEFFICIENCY iteration. It even fares better than the 5.1 liters/100 km (55.38 UK mpg) of the C200 CDI BlueEFFICIENCY (136 hp /100 kW), an engine launched just a year ago.

Also newly available in the C-Class is the C250 CGI BlueEFFICIENCY, a direct injection petrol/gasoline engine. The C250 CGI comes with 204 hp/150kW and 310 Nm of torque while achieving an impressive 7.2 liters/100 km (39.23 UK mpg) fuel rating.

All figures cited above are for the new engines available on C-Class sedan models, fuel consumption is slightly (by very little) higher on the estate/wagon. Still, the competition (Audi, BMW) better keep up lest they leave Mercedes alone to become the go-to brand for consumption-conscious premium brand customers.

Gallery: Mercedes adds new engines to C-Class BlueEFFICIENCY range