Kimi Raikkonen, who won last year's inaugural Turkish Grand Prix from pole position, led the way for McLaren in first free practice at the Istanbul Park circuit on Friday.
The Finn, seeking his first win this season despite starting the last two races on pole, lapped in one minute 28.315 seconds on a clear and sunny morning.
Ferrari's Michael Schumacher was second quickest, 0.462 seconds slower, with Honda's Jenson Button third on the timesheets after celebrating his first grand prix victory at the last race in Hungary.
Renault's world champion Fernando Alonso, 10 points clear of Schumacher in the standings with five races remaining, did not set a time after venturing out as usual for just one installation lap.
Schumacher did just four laps, all in the last five minutes of the session, while Raikkonen did five.
Only 12 of the 22 race drivers set a time as others decided to sit out the session to save engines that must last for two successive races.