Due to the apparent confusion about how many people are permitted to travel in a car during the State of Alarm in Spain, the Guardia Civil has issued this clarification: “Whether or foot or in a vehicle, people must travel alone if they leave their homes for any of the purposes stipulated in article 7 of the Royal Decree which declared the State of Alarm. The only exception is if you are accompanying somebody who is disabled, or for another justified reason. Therefore, only one person may travel in a car unless they can prove that they have a justifiable reason to be accompanied.”
This also applies to essential shopping. It doesn’t matter whether you walk or drive - you can only go alone.
The Guardia Civil have also stressed that nobody is permitted to go running, go for a walk, play sport or take exercise outdoors, even if their doctor has told them to do so. Nor can they take exercise on stairways or in communal areas of apartment blocks.
The law is absolutely clear: people need to stay inside their homes.