Car insurance in Spain is more or less the same as in the UK, or other European countries, and is obligatory. We offer various types of motor insurance to cover cars, vans, motorbikes and 4x4's and motorhomes. As is perhaps the case with your existing car insurance, there are discounts for no-claims and discounts for named drivers as well as increased excesses/waivers.
One difference between Spain and the United Kingdom is that your policy will generally include annual roadside assistance and breakdown cover and it is the car that is insured, not the driver. This means that any driver aged over 25 years who has held a licence for 2 years or more can drive your car. So, if you need someone to drive your car unexpectedly, they can do so as long as they fit the criteria; you don't have to call up the insurance company, wait in a queue and ask for them to be added or pay an admin fee for the pleasure. Relax, they are covered.