Anyone who has been to Europe recently and rented, say, a BMW 7 Series or a Mercedes-Benz S-Class, or even a Volkswagen Beetle or Ford Focus, knows that today's diesels are far more civilized than our irascible Volkswagen Rabbit. In the past decade, diesel technology has revved ahead. It began with European consumers, who were motivated by gasoline prices at least twice those in the United States. European government officials, meanwhile, concerned about global warming, created tax breaks to encourage diesel car ownership (since diesels burn less fuel, they produce fewer of the greenhouse gases, including carbon dioxide, that contribute to climate change). Automakers responded by investing heavily in diesel research, and the new technologies that emerged have virtually eliminated the smell, noise, and power disadvantage of the diesel. Today, 35 percent of passenger vehicles sold in Europe are diesel-powered, and industry experts predict that portion will rise to 50 percent in the next decade.