What worked for me was a leather steering wheel cover, one of those that you lace on, not one of the slip-on kind. If you follow the instructions and lace it on reeeeaalll tight, it stiffens up so much that the looseness of the foam is no longer noticable. At the risk of mentioning a competitor, Performance Producs has these in their catalog. Pay attention to the size, I believe most older MB's will take the larger size.
2004 C240 Wagon 203.261 Baby Benz
2008 ML320 CDI Highway Cruiser
2006 Toyota Prius, Saving the Planet @ 48 mpg
2000 F-150, Destroying the Planet @ 20 mpg
And remember folks, Only You Can Prevent Hilliary.