I have watched the debate over the IDL on several newsgroups including this
zine. I have an IDL; the cost was insignificant at $10 from AAA (and I think
they waived that fee if you are a member). I have not needed it Europe. The
rental agencies do not care if you have it or not. In South America,
however, officials seem to be document crazy; the more you have the better.
So when we were making border crossings, the IDL as another piece of
officialdom was invaluable. If you have the chance to get it, do it. I won't
hurt and if you never need it, all the better. It does not hurt to have
documents of any sort. I have a friend who had a seal made up. It says
Official Seal and sports a picture of a seal balancing a ball on its nose.
You would not believe how many officials have accepted that seal on copies
of documents as attesting to the officialness of the copies.