Hi,
I'm going to stay 3 months in Costa Calma and I'm looking for a long-term car rental.
Do you know any small local car rental, not like Gold Car, Avis etc?
I'd suggest you ask PlusCar for a special price. Their ordinary rates are very good and there's no idiotic insurance surcharges. Contact details at http://www.pluscar-fuerteventura.com/en/ (http://www.pluscar-fuerteventura.com/en/)
You could also try payless.es