A long shot I bet, but I have to ask as I will be there soon.
Erich, I spent a week down there on the Pacific coast last year. Everyone i asked about old cars said there were none, but i would imagine there have got to be a few in San Jose. Enjoy yourself, its a beautiful country!
There is an antique car club that has it's own website. It is www.AutosAntiguos.org
I believe that most of the activity of that club is with newer models of old cars, but there are a few Model Ts in the country. One man that owns a couple is Gaspar Ortuno. He lives in San Rafael Arriba de Desamparados. I have been at his home twice years ago and he has many old cars. He is a very busy man and can be difficult to locate. He lives about 1 block from my sister-in-law. You are not apt to find people out for a jaunt in one of the really old cars there as there aren't a lot of cars from that era, traffic around the San Jose area is horrible and there are lots of mountains and impatient drivers. I've been there 43 times through the years and used to live and study there 40 years ago.