The new 2010 E-Class Coupe is not based on the actual 2010 E-Class platform but on the smaller C-Class's platform. One reason for this is weight while another is marketing.
Speaking with Wolfgang Bremm, E-Class product manager, Automotive News has confirmed that the 2010 Mercedes-Benz E-Class Coupe is in fact based on the C-Class platform, not on the E-Class after which it is named. This is the very same C-Class platform officially called the W204. Renaming the car that replaced the two-door CLK as an E-Class is interesting to say the least, but it follows Merc's previous production of basing the W209 CLK on the W203 C-Class platform.
The new E-Class sedan uses a platform codenamed W212 which is clearly not W204. Speculation is that the E coupe's platform designation is C207.
The question may arise as to why Merc would rename the car after the E-Class when it's based on another. Ernst Lieb, CEO of Mercedes-Benz USA says one of the answers is that the car performs better for its intended purposes with C-Class underpinnings than it would with E-Class architecture. But more telling a reason is that customers will be far more willing to fork out more money for something called an E-Class Coupe rather than one called a C-Class Coupe, especially at the higher end where the margins are bigger.
Weighing about 400lbs (181kg) less than an E-Class sedan and boasting a slicker body, the Coupe will ultimately handle better and be more efficient than its predecessor.
However, due to the growing media attention of this report, MBUSA officials have issued a statement, according to Left Lane News, saying the E-Class coupe shares more than 60 percent of its "components and technology" with the E-Class sedan. In what appears to be an attempt to excercise some damage control and divert some of the attention back to the E-Class the statement fails to address the inner body structure or platform as being W212 or W204.
We tend to believe the original report was accurate and the E-Class Coupe is indeed based on the W204 C-Class despite its common componentry with the W212 E-Class.