Originally Posted by jens
In 2009 it proved to be less efficient than initially thought. All four teams, who had opted to develop and install KERS for 2009 (McLaren, Ferrari, BMW, Renault) were struggling in midfield in the beginning of the season. Needless to say, those teams happened to lock out the whole Top4 in WCC in previous year! McLaren and Ferrari improved later in the season, BMW improved only after they had ditched KERS. So although much of McLaren's troubles were put down on aerodynamics, it was easy to conclude that opting for KERS significantly hindered the progress of factory teams that year.