The rigours of being âultimate driving machinesâ have not always been borne gracefully by BMWs.  Engineered to batter their opponents through chassis refinement and bottomless reserves of grunt, the cars have often worn their styling awkwardly, like Olympic swimmers dressed up for the morning talk show circuit. But with the Concept 4 Series Coupe, which made its web debut in December, BMW clearly wants its athletes to not only look presentable, but pretty.  And the concept, which previews the replacement of the 3 Series coupe, is an unabashed beauty, with curves and musculature in all the right places and proportions. An alloy strake behind the front wheel arch may be the only misstep, an apparent lack of judgment on an otherwise perfectly restrained design.  BMW indicated that even though the Concept 4 Series is a tease toward the next 3 Series coupe, that eventual model will retain the 4 numeral. “It is deserving of the even-numbered badge,” Ian Robertson, member of the BMW board, told BBC Autos after the car’s official introduction on Monday in Detroit. A convertible would be forthcoming, too. The Geneva motor show in early March would be the obvious occasion to show that concept, but Robertson would not play ball. “I think you just have to wait and see,” he said.  Elsewhere at the BMW display, the Z4 roadster, face-lifted for 2013, demonstrated its folding hardtop; the 4-cylinder, 180-horsepower 320i sedan struck a somewhat frumpy pose; and the M6 Gran Coupe rumbled away with a throaty bellow from its 4.4-litre V8.  They were all overshadowed by the belle of the Bavarian ball.
The Concept 4 Series will form the basis of a new coupe, and of vivid daydreams around the world.