Yup, it 's a common and annoying problem. The foam in between the plastic works, as does replacing the plastic panels. As Haasman stated, the squeak comes from the plastic panel that goes around the seat belt area and the sides of the seat. When it ages and wears down, it looses its form/resiliency and it starts to rub - hence the squeak.

__________________
Chris
2007 E550 4Matic - 61,000 Km - Iridium Silver, black leather, Sport package, Premium 2 package
2007 GL450 4Matic - 62,000 Km - Obsidian Black Metallic, black leather, all options
1998 E430 - sold
1989 300E - 333,000 Km - sold
1977 280E - sold
1971 250 - retired

"And a frign hat. They gave me a hat at the annual benefits meeting. I said. how does this benefit me. I dont have anything from the company.. So they gave me a hat." - TheDon