The biggest discount card in Spain in the "Carné Joven": www.euro26.org
To drive in Spain you must be aged 18 or over. To rent a vehicle you must be 21 or over. Many companies also require you to have held your driver's license for a minimum of one or two years. Remember that you will also require a credit card to rent a vehicle.
For buying alcohol or tobacco you needed to be at least 18 years old.
Is possible to work from the age of 16 if you have a parents permission.
You can vote in the elections if you are over 18 years old.