Porsche also offered a drive of the Cayenne diesel, currently on sale in Europe with its 3.0-liter Audi turbodiesel. As with the hybrid, the diesel has plenty of oomph for a big SUV, though this is Audi's V-6 turbodiesel, a 240-horsepower, 405-pound-foot unit, not the legendary V-10 turbodiesel. Like other German manufacturers before it, Porsche is measuring U.S. market interest. If it determines it can sell somewhere north of 10 percent of its U.S. Cayennes with diesels, we could see it by 2011.

If making the next Cayenne less off-roadable than the current model results in mass reduction, performance levels will improve. Porsche touts the hybrid as having V-8 performance with V-6 fuel efficiency; however, its price also will be closer to the V-8's.

So why is Porsche proceeding with the hybrid and diesel Cayenne, even as its lineup inevitably will share Corporate Average Fuel Economy and European Union CO2 averages with VW Polos and Audi A4 diesels? The hybrid system is modular, and it and the diesel will fit in Porsche's Panamera sedan. And Porsche has been hard at work developing a second-generation Cayenne along with the VW Touareg and Audi Q7 since before its management tried to take over VW.

Then there's Dr. Leiters' explanation: Porsche owners want more environ- mentally responsible models from which to choose--the brand must offer clean, fuel-efficient models without relying on anyone else. And so it starts with the model first designed to improve Porsche's financial viability, its SUV.