Er, "wow".  Now that is dedication.  Those also confirmed my suspicions about Aria and Amalfi noted in the List of Gran Turismo courses.  El Capitan is the only one I'm having difficulty tracing.  The location is clearly genuine, though I can't find the actual road that is used for the circuit.  I vaguely remember this being listed under "Original Courses" in GT4, so it's possibly an entirely original course just set in the location.  Are there any identifying marks on the course, such as a route number, that might help in this?