Altogether the reduction of weight was an important factor. By consistent light-weight construction and the extensive use of high-strength sheets a body shell structure weight of 405 kg could be reached. In spite of a significantly improved structure safety this was only 20 kg more than that of the preceding model.
A further important feature of SL-specific occupant protection were the newly developed integral seats, which were designed to provide extra protection in the case of side impact. The seat frame, made of five extremely stiff magnesium castings, made it possible to integrate into the seat the seat belt system including tensioner and belt height adjustment with automatic head restraint adjustment, as well as the all-electric seat adjustment functions. Not only safety was important, but also comfort, the foundations for which had been laid in the design of the bodywork. Additional diagonal members had been included to reduce the vibration and torsional movement typical of an open sports car.
The front axle sub-frame was connected to the door sills and at the rear the spare wheel well was also connected to the door sills. This meant that torsional stiffness was 30 % better than with its predecessor and total stiffness was similar to that of a saloon car.