Mercedes Benz is expected to show us a new 4-door convertible concept prototype based on the current Mercedes Benz S-class at the Detroit Motor Show early next year. The model might go into production with choices of engines that include a performance V12 in 2009, just 2 years from now.

But then again, is Mercedes Benz answering a question that no one asked? Is there actually a demand for a 4-door convertible, and what will having 4 doors do to the car’s structural rigidity?