Sports cars, whether they are two or four door, have long been known not to deliver the best fuel economy. Now that we're in a time where every mpg counts, Audi has taken some interesting steps to make its compact super sport sedan be more environmentally friendly. By switching to a V6 in the latest generation S4, it utilizes a forced induction via a supercharger that allows for 24 mpg.
As such, the new S4 (unlike its V8 predecessor), is able to avoid the US gas guzzler tax. Don't think the S4 is going soft. Quite the opposite. If you ever believed in the "less is more" philosophy, then this is your car.