In early 1996, over 6 years into the life of R129, development work on a successor began. On January 27, 1996 design work commenced and draft designs were submitted from ten designers in Germany, California, and Japan. Hundreds of sketches were submitted and would form the basis for twelve quarter scale models which were digitized for computer manipulation. Design of the R230 would progress through two different formats. The real world process centered on the traditional 1:4 scale models, with most of them initially being done clay. Virtual world design development took place in a room packed with state-of-the-art computer processing technology referred to as the “CAVE.”
The SL underwent a facelift in 2006, and was unveiled at the Geneva Motor Show. Changes include new engines for SL 350 and SL 500 (called SL 550 in North America), with improved performance on SL 55 AMG and SL 600, as well as a new top-of-the-line SL 65 AMG. ABC (Active Body Control) was improved to reduce body movements in dynamic driving by up to 60%, standard on all models except the SL 350. The new engines were mated to a new 7-speed 7G-Tronic automatic, with a Sport option to allow shifting to be performed up to 30% faster in manual "M" mode, and with added steering-wheel shift paddles.