The Mercedes-Benz E-Class cars have been re-engineered from the axles up for the 2003 model year. Mercedes has redefined its traditional best seller with loads of new technology, a sensuously athletic new look and more youthful, vigorous driving dynamics. The E-Class has never been the biggest, fastest nor most technically sophisticated of the Mercedes-Benz cars, but it is surely the most recognizable Mercedes in the world. The company's mid-line E-Class luxury sedan is a fixture from Burbank to Berlin to Baghdad. The E-Class was knocked from the top of Mercedes' U.S. sales chart in 2001 for the first time ever, replaced by the compact C-Class sedan and coupe. The switch, more than likely, is an anomaly. Since World War II, the E-Class has accounted for nearly half of Mercedes' worldwide sales. Without major updates since 1995, the outgoing E-Class might have grown stale in the buying public's eye, and it still averaged 50,000 sales annually for the past five years. The importance of the E-Class in Mercedes' lineup brings an important benefit for consumers: The company spent four full years and nearly $2 billion developing the all-new 2003 model. By any measure, that's serious investment. Clearly, the company in Stuttgart is flexing its muscles for a real show of force. It appears BMW and Audi have cause for concern here.