The system has 44 stations that follow the city's ring road via Avcılar, Zincirlikuyu and the Bosphorus Bridge to Söğütlüçeşme using dedicated bus lanes for almost the entire length of the route.

It has been suggested that Phileas buses, which are now rarely used, were underpowered and not strong enough to carry heavy passenger loads and climb steep hills typical of the topography of Istanbul.

[14] Also in 2009, İETT dismissed concerns regarding their institutional incompetence and the design of Phileas buses, citing "the very high loading at peak hours as the reason for malfunctioning rather than the road slope.

[17] Öztürk pointed out that the guided bus system ensured that Phileas buses were safer than others, and that, even in the case of a front tire blowing out at speeds of up to 80 kilometers per hour, the vehicle would not crash.

[19] In 2017, CHP MP Gürsel Tekin stated that former Minister of the Interior Beşir Atalay, along with other members of the AKP cabinet, twice prevented the Istanbul Metropolitan Municipality (İBB) from initiating an investigation into the matter.

In 2008, civil service inspectors from the Ministry of the Interior uncovered 100 million Euros worth of irregular financial transactions in the İETT, chiefly relating to the purchase of the Phileas fleet.

Their report to the Ministry, implicating high-ranking İETT officials including former president Mehmet Öztürk, indicated that the 63 million Euro purchase was made without a tender.

By the request of the inspectors, a judicial investigation into İETT leadership was initiated by the Beyoğlu Office of the Chief Public Prosecutor, with Öztürk providing a written testimony.