Williams’ official launch took just five minutes in the Jerez pitlane on Tuesday, before the new Renault-powered FW34 had a difficult birth.
"Unfortunately testing was cut short with a couple of initial teething problems which we are currently investigating," said engineer Mark Gillan.
Official testing action burst into life in 2012, with every team except Marussia - and nine all-new cars in action for the first time - kicking off their campaigns.
Returning 2007 world champion Kimi Raikkonen was fastest all day.
"The lap times don’t matter today," Lotus’ Finn insisted.
"I do have a good feeling, and that was not always the case in my career after the first day of testing," he told Germany’s Auto Motor und Sport.
"But I would rather be P1 at the end of the first race than at the end of the first test day," smiled Raikkonen.
Red Bull’s Mark Webber, with the team’s brand new title-defending car only the third quickest of the 2012 runners, agreed.
"If what we saw today happens in Melbourne, then we’ll talk again," he laughed, explaining the missed morning of testing as due to a crucial part being held up at an airport shrouded in fog.
The Guardian also reports that a Red Bull truckie was stopped for speeding.
Lotus team boss Eric Boullier, however, is convinced Raikkonen’s speed is real - and his motivation intact - after two years away.
"Believe me, he is there."
Agreed technical director James Allison: "You can tell Kimi is a class act."
Like fellow top team Red Bull, the new McLaren also had a low-profile day, with Jenson Button just eighth quickest.
But he didn’t accuse Lotus and Raikkonen of showboating.
"Maybe he (Raikkonen) was running heavy," said the 2009 world champion. "We maybe haven’t seen eye to eye a lot of the time when we’ve been racing, but he’s a very quick driver, a world champion.
"He’s obviously in a very competitive car, and whatever they did today - low fuel or whatever - it was still quick."
Struggling on Tuesday was Caterham, whose new car could not be restarted following damage to the engine starter shaft, and Toro Rosso with an oil leak.
And Felipe Massa was just ninth in the new Ferrari.
"It is obviously too early to say if this year we will be able to win or not," said designer Nikolas Tombazis.