The Capital Express (Turkish: Başkent Ekspresi) was one of the six daily intercity trains operating between Istanbul and Ankara on the Istanbul-Ankara railway before the Yüksek Hızlı Tren high-speed train service replaced all intercity trains on the line. The Capital Express was the fastest of the six trains, making limited stops only in large cities. The train would complete its journey in just over four hours and in the Eskişehir Province, trains would reach conventional speeds of 150 km/h (93 mph), which still hold the record for fastest conventional train service in Turkey. When the high-speed rail service was opened between Ankara and Eskişehir on 13 March 2009, the Capital Express, along with the other five intercity trains, were cut back between Istanbul and Eskişehir. During this period two more daily intercity trains were added, the Sakarya Express and Eskişehir Express, increasing daily intercity service to eight trains.

On 31 January 2012, the Capital Express was discontinued due to the rehabilitation of the railway between Istanbul and Arifye. When trackwork was completed in 2014, YHT high-speed service replaced the Capital Express all the way from Ankara to Istanbul.

By the early 1990s, the Turkish State Railways' already bad reputation was worsening. Even TCDD's flagship train, the Fatih Express, running from Istanbul to Ankara, was losing market share to buses and airlines. New modern buses as well as the construction of the Istanbul-Ankara highway nearing completion, made passengers choose bus over train for the route. Even though the Fatih Express made limited stops; the blue-red Pullman fleet, which the train used, was greatly unpopular with the public. The cars lacked proper suspension and air-conditioning, which made journeys in the summer very uncomfortable, due to the generally arid and hot climate of central Anatolia. In the winter, radiators on the train would burn uncontrollably, sometimes even melting shoes rested upon them.

These problems forced the State Railways to introduce a new train service on the line. In 1992, the Capital Express was introduced with new TVS2000 railcars. These new railcars had new bogies with new suspension, which made journeys more comfortable. Along with better suspension, the railcars also had sound insulation, air-conditioning and automatic doors.

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