Complex sentence: Significantly, production of Freightliners also commenced in Santiago Tianguistenco, Mexico, about outside Mexico City, in a plant owned by Daimler-Benz and also producing at that time buses, Brazilian-sourced medium-duty trucks, and compact Mercedes-Benz passenger cars.
Split into simpler sentences: Significantly, production of Freightliners also commenced in Santiago Tianguistenco, Mexico, about outside Mexico City, in a plant owned by Daimler-Benz. It also was producing, at that time, buses, Brazilian-sourced medium-duty trucks, and compact Mercedes-Benz passenger cars.