An Inter-American Driving Permit (IADP) allows an individual to drive a private motor vehicle in another nation when accompanied by a valid license from their home country. Similar to the International Driving Permit, the IADP is used for countries in North, Central, and South America. It is used is association with the driver's personal license, and is not a license to operate a motor vehicle on its own.
So its a good idea to get one of these as I am sure an insurance company will honor it. DR recognizes both Inter-American and International Permits, while some other Latin American Countries only recognize the Inter-American Permit. Both are available from AAA for 15 US$ each. Follow the link.
International Driving Permit