Something in my subconscious kept thinking "Ascari Race Resort..." while watching all this Spain-located content. Maybe because I've read the possibility of such thing in this forums before.
Anyways, I did a bit of Google-ing and found out what is most likely the reason why the PD crew visited Spain, more specifically Ronda:
http://www.ascari.net/google-maps.html
Locations
Ascari is located in the heart of Andalusia, at the centre of the Serrania of Ronda, in the province of Malaga.
The track is 10 kilometres outside Ronda, and the following distances by car from these important places:
Ronda: 7 minutes.
I bet a leg that PD visited Ascari Race Resort. It's obvious. I'm not going as far as saying that they've included the track there (although it would be damn nice!) but most likely they were there to scan the cars kept there by the ultramillionaires that belong to the club. I see no other reason why Ronda would be included.