BARCELONA, Spain (AP) Force India driver Nico Hulkenberg set the fastest time Wednesday in preseason testing for the Formula One season.
Hulkenberg's time of 1 minute, 23.110 seconds was set on super-soft tires in the afternoon session, improving on second-place Romain Grosjean's time by 2.764 seconds.
Kimi Raikkonen, who had spent most of the morning in Ferrari's pit, provided the third-fastest time in the afternoon session, 2.867 off the pace.
Although Jenson Button finished 45 laps in the morning, a sign that McLaren could be overcoming last season's reliability problems, a hydraulic leak marred the 2009 world champion's afternoon session when he added just another six laps.
His teammate Fernando Alonso said McLaren had nevertheless improved the car significantly over the previous year's model.
''I hope to make an important leap forward,'' said Alonso, who added he now felt Mercedes could be beaten. ''I think McLaren Honda can do it, and that's why I'm here.''
World champion Lewis Hamilton managed to complete 88 laps, but was eighth-fastest - having chosen to test only in the afternoon session.
A red flag slowed drivers toward the end of the morning session after Rio Haryanto left the track on the fifth turn. The Indonesian driver, who is beginning his first season in Formula One recovered to complete a total of 78 laps, although his time was the slowest of the 12 drivers testing Wednesday at the Catalunya Circuit.
Kevin Magnussen, who caused another red flag when his Renault ground to a halt on the track's final straight, recovered to set a marginally faster time that Mercedes driver Nico Rosberg.