By David Thomas on September 11, 2009
By Thom Blackett for Cars.com
Today’s diesel engines are equivalent to a prisoner coming up for parole. Years ago, they committed a crime against society, one with lingering effects and images not soon forgotten. After decades of banishment, they make claims of a rebirth, of adopting new ways that will benefit those on the outside. They request a second chance.
With that second chance comes conditions, and for the diesel, those include burning only ultra-low-sulfur diesel fuel, employing advanced emissions systems that drastically reduce the release of noxious exhaust particles, and making them available in all 50 states. Just to make everyone happy, toss in impressive performance and less of that annoying clanging sound that was prevalent in old diesel engines.
It would appear to be a win-win situation, but truth be told, this new generation like the Volkswagen Jetta TDI and BMW X5 xDrive35d are enjoying only mixed results. That’s why Porsche is reluctant to offer U.S. buyers access to its Cayenne Diesel, a new model that constitutes the vast majority of Cayenne sales in Europe. From the outside, there’s not the slightest indication that you’re looking at something other than a gas-powered Cayenne, but packed under the hood is a turbocharged 3.0-liter V-6 diesel good for 240 horsepower and, like the 2011 Cayenne S Hybrid, 406 pounds-feet of torque. Porsche claims a combined fuel economy rating of roughly 25 mpg. While not required in Europe, a U.S.-spec model would feature the same urea-based AdBlue system used in existing large diesels like the Volkswagen Touareg 2 TDI. Smaller diesels like the Jetta don’t require an additive to pass U.S. emissions.
As with the Hybrid variant, we took advantage of Porsche’s offer to drive the Cayenne Diesel around a short loop in Los Angeles. What we discovered, aside from the lack of diesel clatter, was a heavy SUV that delivered tremendous torque, yet didn’t feel all that quick. Plant the accelerator against the floorboard from a dead stop and you’ll notice some definite turbo lag; rolling on the gas pedal elicited a quicker response. The V-6 is mated to a Tiptronic S six-speed automatic transmission that’s been specifically programmed for the diesel’s torque curve.
In comparison with the Hybrid’s electrohydraulic steering, we expected the Cayenne Diesel’s power-assisted rack-and-pinion unit to provide superior road feel and quicker, more linear feedback. To the contrary, the Diesel’s steering felt too light and disconnected from the road. From a handling perspective, we continue to be less enamored with the Porsche of SUVs than rivals from BMW and even Acura regardless of whether they have gas, diesel or hybrid powertrains.
Of course, that will remain a moot point until Porsche decides if and when it will make a Cayenne Diesel available to consumers in the U.S. (even the example we drove was destined for a return trip to Germany). For now, models from BMW, Mercedes-Benz and Volkswagen will be left to demonstrate that today’s diesels are efficient, powerful and clean rides deserving of a second look.
Managing Editor David Thomas has a thing for wagons and owns a 2010 Subaru Outback and a 2005 Volkswagen Passat wagon. Email David