The BlueTec engine features a 16.5:1 compression ratio and is boosted by an intercooled turbocharger. Mercedes also upgraded the turbo by adding variable turbine geometry or VNT (Variable Nozzle Turbine). At low engine speed and load, the vane angles are relatively narrow so the turbine speeds up quickly and creates ample boost without noticeable lag. At higher speeds, a steeper vane angle slows the turbine while increasing intake air volume.

The key reason why Mercedes-Benz BlueTec models are available in all 50 states is the AdBlue injection, which further reduces nitrogen oxide emissions. A water-based urea solution, AdBlue is stored in its own 7-gallon tank which must be refilled every 10,000 miles. Mercedes-Benz explains, “as 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.”

The Mercedes-Benz 3.0 turbodiesel is no slouch either, pumping out 210 hp @ 3800 rpm and 398 lb-ft of torque at a low 1600 rpm. Even with this much torque on tap, it still returns an EPA rated 18 city /24 highway on the Mercedes ML320 BlueTec. With fuel prices rising, and Mercedes-Benz’s huge improvements on the modern diesel engine, it’s not hard to understand why U.S. diesel sales are up 40 percent over the last five years, and still rising. It also explains why Europe now sells more diesels than gasoline engines. Mercedes-Benz is testing North American interest, and if demand continues to rise, you can expect more BlueTec models in the near future.

- Ben DeFresart

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