was n't retained by the eight-time world champions. Which other teams have seats to fill ? Mercedes, Red Bull, Ferrari, Williams, Lotus and Sauber have all confirmed their driver pairings for 2015. There are still seats on offer at McLaren, Force India and Toro Rosso. Force India has already announced it will retain German Nico Hulkenberg for 2015 but Mexican Sergio Perez has not had his position with the team confirmed. There's also only one seat up for grabs at Toro Rosso, who will blood 17-year-old Max Verstappen as the youngest F1 driver in history next season. Junior Red Bull driver Carlos Sainz Jr is in pole position for the second seat -- and the Spaniard has been named as a test driver for Red Bull at the end of season test in Abu Dhabi -- although Toro Rosso may still retain French racer Jean-Eric Vergne. Sauber announced Swede Marcus Ericsson and Brazilian Felipe Nasr as its 2015 drivers in November much to the chagrin of current driver Adrian Sutil, who believed he had a contract with the team for next season. Ericsson and Nasr are both pay drivers, backed by sponsors who bring an estimated $30m funding to the Swiss team. Grid shrinks to 18 in 2015 ? The F1 market may be flooded with plenty of eager racers but the number of seats has been squeezed. The financial pressures on the Caterham and Marussia teams, which both went into administration in October, means there