@Ddey65: no, it was much easier: the cars were bought regulary in a Western country by a special department of the North Korean government, which job is, to purchase Western good for HIM, his family and the rest of the Nomenklatura.
As the plenty of Mercedes Benzes, which are popular for the most upper people since many years.

There is a very interesting book about this -unfortunately not on English AFAIK: http://www.amazon.de/Im-Dienst-Diktators-nordkoreanischen-Agenten/dp/3800074508/ref=sr_1_4?ie=UTF8&qid=1325269166&sr=8-4
Written by the responsible "manager" of this special department. He escaped in 1994 - and lives since then in the underground in Austria.

Nono, it was always easy for the highest ranked stuff to get Western cars and all kind of other Western goods.

Btw: for the all COMECON-nomenklaturas in the times of the Cold War it was not a big deal either. They had all stuff they wanted to have.