Champions Mercedes ended Formula One's first pre-season test with by far the quickest lap time on Friday while Ferrari suffered an engine problem and worried about their pace.
Valtteri Bottas, whose teammate Lewis Hamilton is aiming to equal Michael Schumacher's record seven titles, led the way with a lap of the Circuit de Catalunya only just slower than the all-time track record.
The Finn's time of one minute 15.732 in the morning compared to the record of 1:15.406 he set in qualifying for last year's Spanish Grand Prix.
Bottas had also completed 65 laps, one short of a full race distance, by lunchtime when Hamilton took over for another 73 laps and with the day's second best time of 1:16.516.
Renault's Esteban Ocon was best of the rest, 1.370 slower but with 76 laps on the board.
Ocon's Australian teammate Daniel Ricciardo was seventh fastest after chalking up 93 laps which left Renault executive team boss Marcin Budkowski delighted.
"We achieved high mileage with 169 laps in total and tried the softer compounds ahead of the second test next week," he said.
"Importantly both drivers are happy, the car has a good balance and is performing well and we're pleased with the progress we've made this week."
Max Verstappen, who did 168 laps on Wednesday, again pounded out more than any other driver in the morning with a total of 86.
Alfa Romeo's Antonio Giovinazzi was the big lapper of the day, with 152 for Alfa Romeo.
Ferrari were dealt a setback when Sebastian Vettel broke down with an engine problem, losing valuable track time for the Scuderia.
The final three-day test kicks off back in Barcelona on Wednesday, before Hamilton opens his championship defence in Australia on March 15.
Australian Associated Press
