I've used 44K in my cars since about 1990. A can in the gas tank in the spring and fall kept my assorted Volvos, a Porsche and a VW free of fuel system problems. It was originally introduced to me by a mechanic who worked on a VW my wife drove years ago. I haven't spoken to a mechanic since that did not agree that it was useful stuff. I'll guess MB dealer Mechs say it's no good since MB repeatedly states NO ADDITIVES in their literature. It's worked for me in the tank. I 've never tried the direct method nor had a reason to. I'll try some in the E320 tank this fall unless someone convinces me that it harms MB's? If it is damaging to MB's, I wonder why??