BMW's 3.0-liter, twin-turbocharged diesel straight six has attained much critical acclaim in Europe, and now the company will really and truly offer it in the U.S. Show up at your BMW dealer in December and you'll be healthy to buy both the 2009 BMW 335d and 2009 BMW X5 xDrive35d. And that's it in all 50 states. Both meet the BIN 5 standard using a pair of AdBlue urea tanks.

AdBlue injection systems aren't cheap, of course, so we're not surprised the $44,725 335d costs about four grand more than a manual-shift 335i while offering similar performance — BMW's 0-60 claim for the diesel 3 Series is 6 seconds flat. EPA stats are 23/36. That's all with a six-speed automatic, the only transmission acquirable on the 335d.

The 2009 X5 xDrive35d, er, diesel X5, comes in at $52,025, but since the base X5 lacks the company's twin-turbo gasoline I6, the price jump is easier to swallow. BMW says the diesel X5 will hit 60 mph in 6.8 seconds — as quick as the V8 X5.Rated at 19 city/26 highway, it's vastly more efficient than any other BMW X5 past or present. Additionally, as Auto Observer reported last week, both diesels remember for a tax credit.

Save for a couple guys diving under the X5's hood to spot the AdBlue tanks, the cutely electric Mini E and redesigned 7 Series got most of the attention at the BMW booth. But we're much more interested in the diesel Bimmers. Like BMW's gasoline twin-turbo six, the 2993cc engine in these cars uses both a small and a large turbocharger to create a vast spread of torque, peaking at 425 lb-ft from 1,750-2,250 rpm.

Now that it's 50-state-certified, the remaining question mark is income volume. As the quickest (probably) and most efficient member of the X5 family, the X5 xDrive35d is an cushy sell. But given how good the 335i is, the pricier 335d might not be.

Erin Riches, Senior Editor