Mercedes will launch a revised C-class with a super-frugal 1.6-litre petrol engine in late summer, according to company sources. The new four-cylinder turbocharged engine, dubbed M274, is the longitudinally mounted version of the M270 engine that is also making its debut in the new A-class.
The engine, which features Mercedes’ new Camtronic two-stage variable valve lift, is expected to come in two forms with the same 1595cc capacity. Figures for the C-class haven’t been revealed, but in the A-class the new engine comes in 121bhp and 154bhp versions, producing 128g/km and 129g/km of CO2 respectively.
There is also a 1991cc version of the engine, which is good for 208bhp and 143g/km. Pollution levels are so low that it meets 2015’s stringent Euro 6 emissions regulations.
The company says the engine benefits from three key Mercedes BlueDirect technologies in addition to Camtronic: piezo injectors, multi-spark ignition and a turbocharging system that uses ‘scavenging’ to reduce turbo lag to an absolute minimum. It also has balancer shafts, variable-rate water and oil pumps, low-friction internals and automatic stop-start.
The injectors allow up to five injections for each power stroke and the fuel that is injected is delivered more accurately, does not penetrate as deeply into the cylinder and vaporises faster. A multi-spark ignition system allows up to four sparks to be discharged in less than a millisecond, while the Camtronic set-up offers high low-stage camshaft lift.
Mercedes says that the engine delivers “diesel levels” of torque, with a peak of 184lb ft available in the entry-level engine at just 1250rpm. By partly overlapping the opening times of the intake and exhaust valves, combustion gases can be flushed out of the cylinders and into the exhaust manifold earlier than normal, which helps to spool up the turbocharger sooner.