This has happened twice that I know of. While on the interstate traveling between 70 & 75 mph with cruise on, I noticed in my rear view mirror black smoke billowing out of the tail pipe. This happened for about one to two second's. It only happened that one time each trip. I felt no loss of power or miss in the engine.It was really wierd because had I not been checking traffic in my rear view mirror at the time I may never have noticed it. Any idea's or information would be helpful. I have an 83 300D with 182K miles.
auto\hydraulic mechanic 20 yrs