After Xi 'an takes the expressway to Yuncheng, take the Universiade Expressway, then take the Taiyuan South Ring Expressway to Taiyuan, and get off at Jinzhong Exit. (It should be Wusu Exit D, marked Jinzhong Exit. You can ask the staff of the export department again then. ) Get off at expressway and go to Yu Tai Road. Continue south 10 km to Jinzhong city.
The time is about five hours.