Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan Combining turbodiesel engines with German luxury cars isn’t new, but before the 2014 Mercedes-Benz E250, premium-branded diesel sedans like the 335d and outgoing E350 Bluetec were powered by six-cylinder turbodiesel engines. For 2014, a 2.1-liter turbodiesel I-4 replaces the 3.0-liter turbodiesel V-6 in the Mercedes-Benz E-Class sedan. Considering cars like the Mercedes-Benz E-Class, BMW 5 Series, and Audi A6, we’re wondering whether a turbodiesel I-4 makes sense in a midsize luxury sedan.

Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

 Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

Thread of the Day Is a Turbodiesel I-4 Appropriate for a Midsize Luxury Sedan

 While the E250’s smaller engine gives up little power (down 15 hp and 31 lb-ft of torque) to the outgoing U.S.-spec E-Class diesel V-6 engine, it produces a respectable 195 hp and 369 lb-ft of torque. After sampling the 2.1-liter turbodiesel in our 2014 Mercedes-Benz E-Class First Drive, the engine didn’t feel underpowered, but we noticed a bit more noise and vibration in the cabin compared to the old six-cylinder. More NVH isn’t surprising considering naturally balanced six-cylinder engines – whether inline or vee – tend to idle and rev smoother.
BMW has also announced it will offer a 2.0-liter turbodiesel I-4 in the U.S., alongside a new twin-turbo 3.0-liter six-cylinder diesel engine, though neither engine has been confirmed for the 5 Series sedan.  As for the turbocharged 2.0-liter gas engine in our long-term 528i sedan, we’ve had few complaints other than the abrupt engine stop-start system.
Even with modern advancements in engine design and computer controls, diesel engines can be harsher than similar gasoline engines. With luxury buyers expecting smooth idling and revving engines, is a turbodiesel I-4 appropriate for a midsize sedan? Share your thoughts below.