Been hearing this message on the radio today so thought I would look it up ................

Be aware of ‘highway pirates’ who target foreign-registered and hire cars, especially those towing caravans. Some will (forcefully) try to make you stop, claiming there is something wrong with your car or that you have damaged theirs. If you decide to stop to check the condition of your/their vehicle, stop in a public area with lights like a service station, and be extremely wary of anyone offering help.

Here is some more info from the foreign office...........

https://www.gov.uk/foreign-travel-advice/spain/safety-and-security