I want to buy a car to keep in Spain, I only need an old banger, Im in the mountains of Carratraca which is 30 mins inland (North) of Malaga.  Can any one advise?

Whatever you do - make sure it is 'legal'.
I.e you do all the paperwork as a local would do.
Legally the purchaser has to pay for the transfer of ownership.. this should be done through a 'gestor'.  If it is an old banger it should not cost too much (our new purchase - an 11yr old 1.2 VW polo cost Eu100).. Be aware that the road tax (paid at your local town hall) will have to be up to date, as should the ITV (MOT) before any (good) gestor will touch the transfer.  Make sure you have a proper bill of sale (compraventa) too.  Be aware that any previous/outstanding 'debts/fines' on the vehicle will pass to you as the new owner.. Your gestor should check this out for you as part of their fee. (We paid just Eu45 for the transfer)

Good luck!

Oh -and make sure you have insurance, carry the log book/ITV book around at all times, plus your insurance and your driving licence (plus ID if necessary too!).