Road trip is what we say here in the U.S. Self-driving tour sounds to me as if the tour is driving you around.

A road-trip is just traveling from one point to another, usually at an unrushed pace. A self-guided tour is just what it says. You are touring a landmark, historical region or a place of interest without a human tour guide. And as Susanne stated above, you are usually using printed guide information or a recording.

road trip is more informal -- it suggests people getting together, somewhat unplanned but it could be planned, to drive to a destination. People listen to music, eat snacks, and generally relax during a road trip. Suzanne is right about the self-guided tour -- it is more structured with an audio guide.

thank you Susanne, what about "road trip"?

In USA, we do say, "self-guided tour" which means there is no tour guide. It's generally done on foot at a particular destination. The destination staff generally provides a booklet or printed guide to read along the way. Sometimes, there is a recording to listen to and headphones are given on loan.