we have a three month old 2010 ml350 that all of a sudden started smelling inside like a onion -a bad one at that. our dealer began by bombing the ac - then replacing the cabin filter - then trying a special fumigation from mercedes - only to ultimately find out it is the SLIDING COVER FOR THE SUNROOF. SMEELS TERRIBLE. seems tobe on the mb tech site - 26 or so reported cases. so they took out the sliding cover and now have to find a new one that doesn't smell. the dealer has been great. wanted to share the info, larry