Clipped from www.lonelyplanet.com
There is one company with a base at Faro Airport in the Algarve, that does reasonable one - way car hire into Spain. I had a look at their site and they do have a depot at Valencia Airport.
Please see: http://iberiacarhire.com/Read more at www.lonelyplanet.com
See this Amp at http://amplify.com/u/ehju