Imitation may be the sincerest form of flattery, but at Bayerische Motoeren Werke AG it's making people a little nervous, according to the Wall Street Journal. BMW's 3-Series, the heart and soul of the company's lineup, is under attack. The challengers hope their new models will pry drivers away from the BMW line that has long dominated the small sports sedan market. Name a premium automaker and the odds are that it has just launched or is about to start selling a small upmarket car like the 3-Series. Jaguar is about to bring out its X-type "Baby Jag." Mercedes-Benz has new variants of its C-Class that some call "the best BMW that BMW never built." Volvo's new S60 is the car the Swedes hope will transform the company's image beyond boxy safety. And there are contenders from Japan and elsewhere. The reason for the onslaught, according to the Journal: In an era when sales of lower-priced, high-volume cars are growing slowly, demand for high-end cars is taking off. BMW reckons that sales of premium cars will grow twice as fast as cheaper makes of the next 10 years.