LONDON, England - Jean Todt has revealed an ambition to welcome "one or more" new teams to Formula 1.Although Caterham returned for the final 2014 race in Abu Dhabi, the collapse of the least competitive tail-enders in 2014 reduced the grid from 22 to 18 cars.It triggered speculation that the top teams might be asked to boost race numbers in 2015 by adding a third car to their garage. That prospect has now dwindled, with International Automobile Federation president Todt saying 18 cars is sufficient - for now.CORE GROUPS"We'll get a new team (Haas) in 2016," he was quoted as saying by Speed Week. "So in the worst case we will have 18 cars in 2015 and 20 in 2016. We could also make a new bid to attract one or more additional teams."However, for this to be successful, costs must be cut."Nonetheless, Todt does not want to overstate the significance of the two tail-enders' survival struggles, insisting "it is just part of the sport". Todt said: "Of course I'm not happy about what happened to Caterham and Marussia but such things have always happened."'TEAMS COME AND GO'Toto Wolff, boss of 2014 season champion team Mercedes, agree that, as long as F1 retained its 'core' teams, it would prosper. Wolff was quoted as saying by Maxim: "Teams come and go. I think there is a core group that is really important and that group has been there for ever."That's important to remember."