The Mercedes-Benz W220 was a series of flagship sedans which constituted the Mercedes-Benz S-Class during the early-to-mid 2000's. The W220 was a replacement for the earlier W140 S-Class after the 1999 model year. Compared to its predecessor, the W220 had somewhat smaller exterior dimensions but offered more interior space, particularly in the long-wheelbase versions.
Unlike previous iterations of the S-Class, the W220 was not the company's first model to feature the company's new design theme for the next generation of Mercedes-Benz. This honor was given to the A-Class launched in 1997. Nevertheless, being Mercedes flagship vehicle worldwide (while the A-Class was never sold in North America), the S-Class largely popularized the new theme. It demonstrated a significantly different stylistic mindset, with both exterior lines and an interior design that express elegance and modernity. This can be seen as a response to criticism on its W140 predecessor, which was sometimes labeled as too big and too heavy.
Source: Wikipedia, 2012