Oil will be going one of 3 places. Outside the engine in the form of a leak, inside the engine in the form of burning oil, or into the cooling system (blown head gasket). It will not just magically disappear.

If the engine is consuming the oil at the rate you claim, you'll smell it. You bet. You'll also have that blue haze out the exhaust pipe. A possibility is that you have a turbo seal that's bad, and it's dumping in the cat or muffler. You'd expect to have smoke or power loss issues if so.

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Current stable:
1995 E320 157K (Nancy)
1983 500SL 125K (SLoL)

Gone but not forgotten:
1986 300SDL (RIP)
1991 350SD
1991 560SEL
1990 560SEL
1986 500SEL Euro (Rusted to nothing at 47K!)

Gone and wanting to forget:
1985 524TD 167K (TotalDumpster™) [Definitely NOT a Benz]