If you put Barcelona car scam into Google this is what you get, I know loads of people who have been caught out by it.
"Like so many, my wife and I have had an excellent trip to Barcelona. Enjoying the sights and restaurants. Remaining ever so aware of the threat from pickpockets we toured the city without bags etc on display and avoided the experience of street crime. That is until we left Barcelona in a hire car.
Our route out of Barcelona was via the 'Diagonal' heading toward the A7 motorway. As we pulled away from the last set of traffic lights before joining the A7 I realized that one of the rear tyres had a puncture.
For safety I pulled over on a slip road leading off the motorway so that I could contact the hire company and change the wheel. As usual the spare tyre was located inside the boot requiring that our luggage had to be taken out of the boot.
For security I placed the hand sized luggage inside the car and the suitcases safely to the side of the car. As I was lifting the spare tyre out of the boot a motorcyclist approach the rear of the car and offered help as he said he was a mechanic.
I refused his help but he probably distracted me and my wife for about 15 or 20 seconds before he rode off.
When I had changed the wheel I found that a bag had been taken from the car and a mobile phone. On reporting this to the local police I find that I was the victim of a deliberate puncturing of the tyre, which is usually done by a motorcyclist when the car is stopped at traffic lights. Of course by pulling in at the first safe place I set myself up for the scam which clearly involved a 2nd person in hiding near where I would stop.
Having been so careful I felt such a fool for falling for this scam, but I was told by the police it happens several times each day. Several lessons learnt from this experience, but most importantly if leaving Barcelona by car do not have maps on display inside the car (the only way I could have been recognized as a tourist) and keep the car locked even when you are with the car"