For Colombia I have no information, Chile or Paraguay ( Travel Expeditions: How to buy a VW Campervan in Paraguay ) is possible yes. The border Arica-Tacna is sometimes difficult and there are stories that people could not leave the country. The last I heard was of a german couple with a chilean car who got a 6 month exportpermit at that boirder which can be a problem if you want to stay away for a longer period. The border to Argentina or Bolivia is as far as I know still fine.

I have lived in South America for about 10 years and 3 years ago myself and a friend drove from the Caribbean coast of Colombia through the Andes (Ecuador - Peru - Bolivia - Argentina).

I bought the Land Rover (Series IIa 1964) in Colombia. You can get really good ones for about $3000 upwards - ready to hit the road - no probs. Paperwork in Colombia is nice as the seller has to put the papers into your name - or someone, preferably a foreigner with a Colombian CEDULA. Get an older car as it is less attractive to thieves, easier to maintain, built like brick sh*t-houses and you can sell them on without losing out. You are required to take out SOAT insurance in Colombia.

It was the 3rd time I have traveled the length of the Andes and having a 4x4 with camping gear, oven, water etc is by-far the best way of traveling.

You will need your UK driving papers and a post office over-seas permit. If you take travel insurance (this will serve as car insurance too). Don't judge me - its easier than having to pay thousands of pounds and/or having the car impounded.

Make sure that when you cross ANY boarder in South America that you get a SALVO DE CONDUCTO. All other papers are straight forward. Without the Salvo you will find yourself in very hot water. I ended up in prison for 30hrs once.

Do not try to re-sell cars in Argentina. You have to nationalize the car and its not worth the hassle. Go to Bolivia, Uruguay or Paraguay for easiest sell-on or preferably back to Colombia if poss.