Formula One World champion Sebastian Vettel drove his new Red Bull for the first time on Thursday with the team saying they were on course to tick all the right boxes in pre-season testing at Jerez.
Spain's Fernando Alonso finally got his hands on his new Ferrari as well but the Italian team were far less happy with the data coming from the F2012 on day three at the southern Spanish track.
McLaren's Lewis Hamilton sounded cautiously optimistic after his first day of testing following team-mate Jenson Button's stint in the car while Brazilian Bruno Senna marked his Williams debut by doing more laps than anyone else.
"It's been two months since we were in the car so it does take a couple of laps to get back in the rhythm, but the car feels fine and as we expected," said Vettel, who was second fastest of those in the new cars.
Germany's Nico Rosberg topped the timesheets in last year's Mercedes, with Frenchman Romain Grosjean second quickest in the new Lotus.
"So far we can be happy. We had a couple of issues but it's normal when the car is new," said Vettel.
Red Bull's head of race engineering, Ian Morgan, said the penultimate day had gone well.
"Sebastian's first day in the car went almost perfectly," he declared. "Tomorrow's programme will be more of the same. We're on course to tick off all the things we wanted to get done and we hope we can complete the list tomorrow."
Ferrari, with plenty of Spanish fans in evidence on double champion Alonso's first day in the car, were still wrestling with setup problems.
"I am not happy with where we are at the moment," said technical director Pat Fry after Alonso did 67 laps and was seventh fastest. "I think there is a lot of room for us to improve from where we are."
Hamilton covered 80 laps and 354km in the MP4-27 and said his initial feelings were "pretty positive".
"There were no nasty surprises, which is pleasing," added the 2008 champion, whose team were struggling at the same stage last year.
"This car's baseline is something we can really work with."
Senna, nephew of the late triple world champion Ayrton who died after crashing his Williams at the 1994 San Marino Grand Prix, had a productive first day in the car with 125 laps completed without any hiccups.
The same could not be said for Force India's French reserve Jules Bianchi, who brought his team's testing to a halt after crashing into the tyre barrier in the morning.
The team were unable to get the car back out on track as they needed fresh parts from Britain, a setback that meant German race driver Nico Hulkenberg was unable to start his testing programme.