You can add window film that will add UV protection.

Direct sunlight will fade almost anything including leather, have you checked out solar shades they allow you to see out but depending on the weave you choose can cut up to 90% of the UV rays and also the heat.These can be mounted on the exterior if you don't want them inside, the other choice would be a really good quality film as mentioned above.

Visit www.vista-films.com to find a professional near you that can make a recommendation on the best product to use. Window films offer the best protection against fading that allows you to keep your view.