Changes

Another option is taking the "cercanias" or "renfe" C-3, which leaves from Sol, to the Station "Valdemoro". The ticket should cost 3,30 € and it takes 30 minutes to get to "Valdemoro" . Get off the train and walk down "Paseo de la Estacion", take a slight left onto "Calle República Argentina" (the road right next to the highway) take a right to follow "Calle República Argentina". After 100 meter turn left onto "Avenida de Andalucia" and follow it until you get to the gas station. In total it is a 30 minute walk(going uphill, exhausting in summer). The gas station is right next to the highway. There is also a big truck stop. There are also many The station has mostly local people(as it has a car wash) and is usually quite empty, but you will find somebody (going to Ocana) who will take you to the next service station.  In any case, try to get to the Sesana service station, it's on the motorway 4, between Valdemoro and Ocana. Although it is small, it has a good spot when restaurant, and unlike other service stations in the South of Madrid, you want to go down Southwill find long distance rides there (Granada, Cordoba) with some patience.