Outside of the US or Europe, if you can produce a COLOR photocopy of your registration and title, and notarize it...you will be Golden!
Most of these countries have no clue what a vehicle title from the US looks like, let alone know that each state issues their own. BUT the facade of official documents makes your life easier!
I kept about 10 of these with me on my recent trip...and it made processing through customs less of a hassle.
And remember, these guys at the border more often than not are simply doing their jobs as per the rules of their country. The fact that a foreigner walking up to them not knowing the rules OR the language, makes it difficult to process your entry.
So show patience, smile and pat them on the back often, and the process will be less stressful.