The pictures I have seen of Benzes in German show the triangle to be mounted in the trunk lid. Like the tool kits on BMWs. So when you break down on the side of the road, the triangle is displayed to on coming motorist when you open the trunk to get to the spare tire.
1994 MB E320 Coupe (199,500 mi)
1992 MB 190E 2.6 (173,000 mi)
1983 Porsche 911SC (148,000 mi)
2004 Volvo V70 2.5T (198,000 mi)
President of CT/Westchester Section