I too would have said I did not need navigation devices until I spent a lot of time driving in the UK and France the last two years. Certainly in the UK, there is not a 90 degree intersection in the whole country. I first started driving there with a friend who was less than an astute navigator. We were lost more than found.
The next time I went over with my wife and I took a Garmin Streetpilot mapping GPS. Life was totally different. I think it was an inexpensive investment in marital harmony. We were never lost and it could tell us where the nearest fuel stop and grocery stores were. A definite must in Europe.

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1977 300d 70k--sold 08
1985 300TD 185k+
1984 307d 126k--sold 8/03
1985 409d 65k--sold 06
1984 300SD 315k--daughter's car
1979 300SD 122k--sold 2/11
1999 Fuso FG Expedition Camper
1993 GMC Sierra 6.5 TD 4x4
1982 Bluebird Wanderlodge CAT 3208--Sold 2/13