Two Convertibles with some similarities, but otherwise different in most aspects such as the model year, horsepower, ground shadow size, and maximum occupancy. First of all, the 2016 SL-Class has a more powerful engine than the 2013 6 Series Convertible. Also, the 6 Series Convertible has a slightly larger body than the SL-Class. In addition, the BMW 6 Series Convertible seats two more passengers than the Mercedes-Benz SL-Class. Among similarities are the body structure, market segment, starting price, fuel economy, and height.