When BMW AG Chairman Norbert Reithofer declared last week that his company would start making front-wheel-drive BMWs, there were screams from Stuttgart to Sacramento. BMW, after all, had built the Ultimate Driving Machine franchise on rear-wheel-drive cars. Now Mr. Reithofer appears to be chipping away at what made luxury cars so luxurious. Auto enthusiasts—including many automotive designers and engineering executives, as well as wealthy car buyers—generally prefer cars to have the driving wheels in the back. It makes a difference in the way a car handles and steers. That difference is instantly recognizable but hard to define. A rear-drive car...