The newest Mercedes-Benz E-Class in E250 BlueTEC sedan guise has achieved an estimated EPA rating of 45 miles per gallon on the highway and 28 mpg around town.

The first diesel E-Class to be available with 4MATIC in the U.S. achieves best-in-class fuel efficiency for a midsize luxury sedan and for the entire industry in the same size range, according to Mercedes-Benz.

When equipped with optional 4MATIC all-wheel drive, its fuel mileage numbers are 42 mpg highway and 27 in the city.

The E250 BlueTEC is powered by a high-efficiency turbodiesel engine. The all-aluminum, in-line four-cylinder engine makes use of four valves per cylinder and dual overhead camshafts with vane-type variable valve timing, producing 195 horsepower and 369 pound-foot of torque.

Mercedes-Benz said two Lanchester balance shafts spin at twice crankshaft speed in sophisticated, lowfriction roller bearings to smooth out the inherent vibration of an in-line four-cylinder engine. During normal operation, the advantages of this two-stage turbocharged system can be felt – no turbo lag, fast throttle response, a broad torque curve across the entire engine speed range and noticeably improved performance. The 369 pound-foot of torque is readily available at 1,800 rpm.

Fuel pressure for the BlueTEC direct fuel injection system is 2,000 bar or 28,400 pounds per square inch, which contributes to make possible even more power and lower exhaust emissions. Mercedes-Benz said higher ignition fuel pressure means the four piezo injectors can be adjusted even more precisely as engine load and speed change.

To ensure the E250 BlueTEC meets exhaust emission regulations in all 50 U.S. states, the BlueTEC system uses AdBlue injection to make the diesel, per Mercedes-Benz, as clean as a state-of-the-art gasoline engine.

Newly accessible through the fuel filler door, a water-based urea solution, AdBlue, is carried in its own small tank and metered into the exhaust in minute quantities, so the tank only needs to be refilled during routine scheduled maintenance.

When AdBlue is injected into pre-cleaned exhaust gas, ammonia (NH3) is released, converting nitrogen oxides into harmless nitrogen and water in a downstream catalytic converter. Called SCR, for selective catalytic reduction, Mercedes-Benz said this process creates the most effective method of exhaust gas after-treatment currently available.

The new E250 BlueTEC sedan is the price-leader in the E-Class family, at $51,400; the E250 BlueTEC 4MATIC sedan goes for $53,900, both excluding destination & delivery of $925.

For comparison, the E400 Hybrid sedan (rear-wheel drive) will be priced at $56,700.