BMW built its reputation on the excellence of its inline 6-cylinder engines, yet today it introduces new generations of its 525d and 528i with 4-cylinders. These engines are about to become BMW’s spearhead in the quest for better fuel efficiency. Displacement is 2 liters, with turbochargers and direct fuel injection to make power and torque like a bigger unit.

The 525d and 528i are both big sellers in Europe. The first one, the diesel, makes 218-hp and an incredible 332-lb/ft of torque at a low 1500-rpm. All that from a tiny 2-liter engine, thanks to 2 turbochargers. A small one that operates at low revs, and a larger one running at higher rpm. The engine in the 528i has only one turbo, but that one has twin-scroll technology, which makes it function like 2 smaller turbos, one for 2 cylinders. It makes 245-hp and 258-lb/ft of torque at 1250-rpm.

These new engines may not have the sound of their famous 6-cylinder ancestors, but they shine in fuel economy with an official 34 mpg combined rating in the European tests for the 528i. Pretty good for a family sedan which can sprint to 62-mph in 6.2 seconds. The diesel 525d does even better, with a fantastic 47 mpg combined rating. An amazing value for a car this size, with a 150-mph top speed.

Those values corresponds to the 5-series sedan (ours pics show the 525d wagon) with standard 6-speed manual transmission and standard 16 inch wheels. A Stop & Start is also standard in both models to get such low consumption, with accordingly low C02 emissions. No word yet about the 525d crossing the Atlantic, though the 528i will.