For years, Audi has suffered from an inferiority complex in the U.S. It didn’t feel it was getting any respect from potential buyers.

    Lately, it has been attacking its image issue the way a car company should: with smart new products, clever marketing, and a superior customer experience.

    Audi hasn’t yet jumped up to the top tier alongside Mercedes, BMW, and Lexus. It needs a stronger identity and greater visibility. But it is definitely on its way. As the Audi folks would put it, they are moving their brand from a guarded secret, discrete luxury, and the great unknown to mainstream luxury, public prestige, and the great known.

    Personally, I like the idea of Audi as the un-Mercedes or un-BMW. It’s the car for the confident car buyer who doesn’t wear his brand affiliation on his sleeve and adores the functionality of its all-wheel drive.

    Case in point: the 2010 Audi S4.

    Let’s get one issue out of the way quickly. German luxury cars are expensive and the S4 is no exception. At $53,450, my test car cost as much as two similarly-sized Ford Fusions.

    But the S4 is a fully-realized upscale sport sedan. Its supercharged 3.0 liter six-cylinder engine rockets it to 60 miles per hour in 4.9 seconds. The car threads needles with its steering, provides a smoother ride than usually accompanies that kind of performance, and looks great sitting in your driveway.

    More than most other automakers, Audi has mastered the knack of timelessly elegant designs that look good even as they age. The S4 has a much-refined version of Audi’s horse-collar grille and its appearance improves as your eye moves from the front of the car to the rear. It is clean, sophisticated, and eye-catching.

    Note to potential shoppers: The S4 is not the same car that it was in earlier incarnations. The last version was powered by a 340-horsepower V-8 that made it more of a street brawler, ready to do battle with BMW’s hot M3.

    The 2010 version provides nearly the same performance but with much less visible effort. The car is quieter, less expensive by a couple of thousand dollars, gets better fuel economy (18 mpg city/28 mpg highway), and doesn’t require a gas guzzler tax.

    In its new configuration, the S4 now faces off more directly against BMW’s more subdued 335ix. Those who like more excitement in their cars will be disappointed. The S4 no longer has race-car pretensions with the noise and discomfort that often accompanies it.

    Those who prefer discrete luxury, however, will be pleased.