A follow up to the post from Kevin & Julia "Globebusters" regarding the libreta.
I can confirm this document is the equivalent to the carnet in South America & is issued only be the national motoring clubs who form FITAC (Federacion Interamericana de Touring y Automovil Clubes). There used to be a summary of the document on their website, but seems to have been moved/deleted ?
RAC continues to get mixed feedback on use of the carnet in South America. As stated by Grant & Globebusters, it is possible to transit without one !
However, if a carnet is used to enter a country, you should ensure you exit that country before carnet expiry. Peruvian Customs impounded Richard Heaphys' bike last August in these circumstances.
Senior Travel Administrator - RAC Carnets