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antp
You can do that using the search page, in advanced search, and search for cars containing "(USA)" in the "extra info" field.
It would of course work better / be easier if there was a field dedicated to the country.
DIEHARD
Perhaps it is an idea to include a country search in the search function? I would like to find for example Renault, Peugeot and Citroën in the USA. Is it possible to add something like this?