You might dispute whether Volkswagen is a premium brand or not, but few could dispute whether the Touareg is a true premium SUV. Based on a platform shared with the Porsche Cayenne, this off-roader runs with the best; modesty was never its strong point. In Europe and Asia, there is a gasoline W-12 version, rated at 450 horsepower, and the V-10 TDI with its 310-hp engine producing 553 pound-feet of torque was the king of diesel SUVs until its sibling, the Audi Q7, changed the rules with a titanic 500-hp V-12 TDI with 738 pound-feet of torque.

But now VW is adding a nice, socially conscious version to the Touareg lineup. The 3.0-liter V-6 clean diesel launched at the L.A. auto show gets 25 mpg on the highway and 18 mpg in the city, and VW claims it is one of the cleanest engines available on the market. It is 50-state legal, partly through the use of a costly catalytic converter that nearly eliminates NOx emissions, although it is interesting to note that it is sold in Europe without the converter, since it won’t have to meet strict emissions standards there until 2014.

Such catalytic converters are the key to gaining diesel compliance in the U.S. market, and German carmakers are all working on or implementing similar systems, which should finally help to dispel notions of the smoking, dirty diesel for good. The Touareg’s 3.0-liter diesel has been applied successfully to various VW and Audi models. In Europe, it currently is available in the VW Phaeton, as well as the Audi A4, A5, A6, A8, Q5, and Q7. Despite the Touareg’s considerable heft, it moves quickly and effortlessly. Driven by 225 horsepower and 406 pound-feet of torque, the V-6 TDI reaches 60 mph from a standstill in a claimed 8.5 seconds. Top speed is governed at 130 mph.

The Touareg V-6 TDI is a remarkably smooth SUV. There is almost none of the characteristic growl that distinguishes the Touareg V-10 TDI from its gasoline-powered competition. The main reason for this is the injection system. Although the V-10 TDI uses unit injectors, a technology on which Volkswagen has suspended further development, the V-6 TDI gets its fuel served up by a common-rail system operating with piezo injectors. This allows VW to optimize the combustion for smoothness.

This Touareg is nice to the environment, it won’t bother anyone with excessive noise levels, and it’s still a fun-to-drive SUV. Porsche will put this engine into its Cayenne SUV in the near future. Porsche might still not have a V-10 or a 12-cylinder engine, but at least it will be able to offer a fuel-efficient diesel SUV as well. If you take into account its more modest design and its beautifully executed interior, we believe there will be a strong case for the Touareg V-6 TDI even after the Cayenne is launched with its engine.