True sports car enthusiasts assert that true sports cars must have manual transmissions. A shift-it-yourself gearbox can indeed be a major plus when the primary goal is having fun behind the wheel. The installation of a five-speed manual in the Mercedes-Benz SLK for 1999 silences the purists and does much to raise the little two-seater's fun quotient.Among two-seat roadsters, the SLK has two rivals in price, performance and features-the BMW Z3 and Porsche Boxster. The Audi TT will soon join these three.Click here to read more