A Nav system was never factory installed or available for U.S. spec W140s.

As said before, a Nav system was available in Germany and other markets. What I am not sure about is exactly when it debuted, but I would guess it had to be mid-1996 to late 1996, as many 1997 and 1998 model year cars list this option on the used sale sites in Europe.

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A. Rosich
CL 500, 1998
S 500 L, 1998
E 320 T, 1995 [Sadly sold ]