Two Convertibles with some similarities, but otherwise different in most aspects such as the model year, modifications, horsepower, fuel economy, height, and maximum occupancy. First of all, the 2013 RS 5 Convertible has bigger and thirstier engine; the 2016 SLK-Class AMG SLK 55 gets 4 more mpg. Also, the roofline of the RS 5 Convertible is slightly higher than the SLK-Class AMG SLK 55's. In addition, you'll seat two more passengers in the Audi RS 5 Convertible than in the Mercedes-Benz SLK-Class AMG SLK 55. Among similarities are the body structure, market segment, and starting price.