De Wikitravel :
Metro Turizm is a Turkish bus company that runs daily bus service to and from Istanbul in Turkey. Buses going from Plovdiv to Istanbul depart from Jug Station daily at 11:00, 14:00, 19:00, 22:30, and 1:00. The trip costs 40 YTL (as of the summer of 2011) and takes roughly 7 hours, depending upon the vagaries of traffic and the border crossing. Metro buses also depart daily for Bursa, Turkey at 19:00. A second bus line (Alpar) also has a daily bus from Jug Station to Istanbul that departs at 22:30.
Por causa da longa travessia da fronteira com a Turquia, a viagem pode levar várias horas adicionais.
Os ônibus da Metro Turizm parecem começar em Sofia. A estação de ônibus tem um bom site (clique no canto superior direito da caixa suspensa em inglês).