Full/Full Fuel car hire from Gibraltar for longer than 3 days?

Hello,  I travel regularly to the Costa del Sol particularly to Puerto del la Duquesa, Nr Estepona.

I am taking 16 guys golfing next May 2012 and we are flying into Gibraltar. We want 4 x Citroen Berlingo's or Renault M Scenic or similar or 2 x Mercedes Vito Minibus. But we won't be using hardly any fuel up because we are playing mainly around Sotogrande and staying only 20 minutes from the airport.

Does anyone know of a company that will do me this deal? Please!