Finding a safe place to sleep on a road trip can be challenging, especially overseas. If you are in this situation plan your trip so that you come across a larger city towards nightfall. Most mid-to-large cities have airports (even in the third world) and you can park your car and sleep in the lobby.
Airports are easy to find, almost always open 24 hours, and provide you with relatively reliable security. Free (and clean) restrooms, clocks, some places to eat and coffee as well. Finally, you are guaranteed at least a few other people around so you don’t have to sleep alone.
Flyers, find the best places to sleep by your gate.