With a secure power retractable hardtop, the 2009 Mercedes-Benz SLK-Class roadster offers more refinement and civility than either the BMW Z4, Honda S2000, or Porsche Boxster. It also provides a luxurious interior and performance similar to that of the larger SL. And the SLK ranks as one of the safest convertibles on the market, with head-protective side air bags.