Audi is definitely leading the world in diesel-engine development in terms of sheer performance. Edmunds explains that the German automaker is showing gasoline engines should soon be little more than a memory:

Consider those for a moment. The diesel-powered Audi A8 4.2 TDI is not only more economical than the gasoline-powered A8 4.2, it also produces fewer greenhouse gases and, most importantly for readers of this Web site, it’s also significantly quicker.

More importantly, perhaps, is the contrast between European and American energy policy and consumption:

For the past few years, while the U.S. has been bemoaning ever increasing gas prices, the Europeans have been experiencing a quiet, bloodless diesel revolution. The introduction of multivalve, common-rail direct-injection and pre-ignition technology has transformed the diesel engine from a noisy agricultural workhorse into an ultrarefined, economical powerhouse worthy of the finest performance and luxury cars. Across Europe, more than a third of new cars now stop at the black pump and in some countries, diesel cars outsell petrol.

People around the world used to buy American cars because they stood for something — the image of freedom, liberty, and love for the open road, etc. — not because they actually liked the technology or trusted the companies. Now that the Bush administration has all but completely destroyed the positive image of America, and thus washed away the base of competitive advantage US car companies had, global consumers are likely to buy cars that make more sense. Passenger diesels definitely fall into that category. Well, I guess that begs the big question of regulation, security and the rational consumer, but that’s probably best discussed another day.

Edmunds also gives a nod to BMW’s diesel performance:

Today, the economic rationale in favor of diesel is still relevant, but it’s been joined by more emotive impulses. In the U.K., for example, the BMW 530i and 530d cost similar money. They have the same power output (231 hp), but the diesel has dramatically more torque — 212 lb-ft vs. 384 lb-ft. The 530i gets to 62 mph 1.3 seconds quicker than the 530d (which takes 7.8 seconds), but in the midrange, when the torque becomes more relevant, the diesel car pulverizes its petrol rival. That it’s astonishingly refined, even at idle, and achieves an average of 42.2 mpg to the 530i’s 32.1 mpg (European “combined” estimates for manual-transmission vehicles), is really the cherry on top of the icing on top of the cake. The 530d is the enthusiast’s choice, pure and simple.

Had American politicians had any sense about them, clean diesel engines would be a mandate. It’s a clear path to reduce consumption and emissions with little/no impact to consumer preferences for high-performance vehicles. And with 2008 VW diesel technology already being spotted with “extensive exhaust aftertreatment, including catalyst, particle filter, etc, but no urea injection” there is little reason not to get excited about biodiesel…