Which country produced the most expensive car in 1970?
the most expensive refers to max(price); in 1970 refers to model_year = 1970
SELECT T3.country FROM data AS T1 INNER JOIN production AS T2 ON T1.ID = T2.ID INNER JOIN country AS T3 ON T3.origin = T2.country INNER JOIN price AS T4 ON T4.ID = T1.ID WHERE T2.model_year = 1970 ORDER BY T4.price DESC LIMIT 1