There is a car sharing service called bla bla car
At the moment I have a friend here with me here from Puerto Rico.
She came to Granada from Alicante for 21 euros.
Tomorrow she is going to from Granada to Cadiz for 17 euros
(The normal price is 38 euros by bus)
It seems a great way to meet people and get cheap travel.
The website is.http://blablacar.com