The deceased were identified by initials M.G, S.K, and K.D, according to local reports.
Police said that no marks of beating or cutting and piercing tools were found on the bodies but they detected exhaust fumes in the car.
They also said that many alcohol bottles had been found in the vehicle.
The bodies were referred to Ankara Forensic Medicine Institute for postmortem examinations, officials said.
An investigation has been launched into the incident. (ILKHA)