Barcelona: Triple world champion Lewis Hamilton went faster and further than anyone else as his Mercedes team again led the way in pre-season testing on Tuesday while some others struggled to get into gear.
After the team completed 152 trouble-free laps on the opening day, Hamilton returned for a colder and windier morning session and pounded out another 66 - a race distance at the Circuit de Catalunya.
Ferrari's 2007 world champion Kimi Raikkonen, who was second fastest for Ferrari, was 1.848 seconds slower and also did the second highest tally of laps before lunch - 47.
Hamilton's best lap was one minute 20.983 seconds, compared with a timesheet-topping 1:21.765 on Monday. The fastest time in 2016 testing in Barcelona was 1:22.765, showing how much faster the new cars are with bigger tyres and revised aerodynamics.
Red Bull and McLaren, who had a troubled debut day, were still not firing on all cylinders.
Dutch teenager Max Verstappen did 31 laps for Red Bull but Belgian rookie Stoffel Vandoorne was halted after 29 in the McLaren. His car had earlier been pushed down the pitlane by mechanics.
Partners Honda said the car had suffered a power unit problem.
"At the moment we don't know what has caused the issue. We are currently changing the power unit in order to investigate fully and identify the cause," said a spokeswoman.
Vandoorne's unhappy team mate Fernando Alonso had been unable to set a timed lap on Monday morning due to an oil system problem while Red Bull's Daniel Ricciardo suffered a sensor issue.
While those two teams at least got out on to the track, others wrestled with garage gremlins.
Renault's Jolyon Palmer managed to do one untimed installation lap after the team flew in new parts overnight.
Italian Antonio Giovinazzi, standing in for the injured Pascal Wehrlein at Sauber, did five with the team swapping out the Ferrari power unit.
French driver Esteban Ocon brought out red flags with 15 minutes remaining when his Force India stopped on track.
Canadian teenage rookie Lance Stroll spun off after 12 laps, going through the gravel backwards and damaging his Williams.
"We’re having to send some composite parts back to the factory, which will be back with us at some point tomorrow," said head of performance engineering Rob Smedley. "We’re doing the upmost we can now to get back out on track at the earliest opportunity tomorrow."