McLaren, as if anxious to impress their recruit Eric Boullier as racing director, not only managed to start their car on Wednesday but also put in the fastest time of the day at the Circuito de Jerez, with Jenson Button completing 43 laps in the all new MP4-29.

Button's time of 1min 24.165sec was quicker than Kimi Raikkonen (Ferrari) and Valtteri Bottas (Williams), though fourth-placed Nico Rosberg (Mercedes) was probably the happiest driver of the day, completing 97 laps. Altogether, there were 331 laps driven compared with a mere 93 on the opening day of testing, when teams were struggling to work out their new-fangled machines.

Button, who was unable to drive at all on the first day of testing because McLaren were unable to start the car, said: "I enjoy driving this car. The power unit doesn't sound as good. That's a fact. It's not as exciting, from the outside. But when you're driving it, it sounds good. It's actually quite a nice change.

"And the power of the engine is also nice. It's very torquey – it feels the most powerful engine I've driven, though it obviously isn't in terms of outright power. Today was a very useful day. Everything is new. It's not just a new car. Everything is new with this car. I'm amazed we were able to go round and do as many laps as we did today. I'm also driving tomorrow morning."

McLaren's good day must have felt even better with the news that Red Bull had another bad day. Sebastian Vettel, who managed only three laps on Tuesday, completed eight on Wednesday before the team gave up running because of an energy recovery system failure with their Renault engine. At this stage a year ago the world champion had driven 174 laps. So far the Mercedes engine has had a lot more running here than those made by Renault and Ferrari.

Button welcomed the news about Boullier when he said: "The team will never be changed by one individual. But I think he does add something. It's good to have fresh ideas." McLaren confirmed on Monday that Boullier would be joining the team, having resigned his position as team principal at Lotus a week ago. He will not be team principal, the position currently held by Martin Whitmarsh, though confirmation of his pay-off will be made soon following a frustrating five years for the Woking-based factory.

As revealed in The Guardian last week, the choice of Boullier was mainly that of the Bahrain royal family's Mumtalakat investment company, which owns 50% of the group. Boullier is well connected in Bahrain, where he has been involved in a number of sponsorship negotiations.

That means there is still a vacancy for the job of actually running the racing side of affairs and a new position, chief executive officer of McLaren Racing, has yet to be filled, giving fresh impetus to the old rumour that Ross Brawn, who left Mercedes at the end of last year, will be handed the job.

Boullier will be in charge of the team on a day-to-day basis and will be the leader on the pit-wall for races. The new appointment, who will not necessarily attend every race, will have a wider brief, including the development of the car and drivers' contracts.

In a statement on Wednesday McLaren said: "Eric is one of the most capable trackside leaders in Formula 1. He has played the central role in Lotus F1 Team's recent successes and brings with him extensive single-seater motorsport experience, having worked in senior positions in World Series by Nissan and A1 Grand Prix before moving up to Formula 1."

Boullier said: "First of all I regard this appointment as an honour, a privilege and a wonderful opportunity. The McLaren Racing workforce and the facilities at the McLaren Technology Centre are world-class and I'm hugely excited about the prospect of joining such an outstanding team. I'm both eager and determined to play an active part, working alongside McLaren Racing's other senior managers and directors, within a new operational structure, to bring about the changes that will deliver success. Last, I want to take this opportunity to assure the McLaren Racing workforce that I'm utterly determined to match their famous passion and commitment to win."

Ron Dennis, the chairman and chief executive officer of the McLaren Group, added: "Eric's appointment is an integral part of a senior management restructure within McLaren Racing.

"I've already personally conveyed to the entire workforce of the McLaren Group, which includes McLaren Racing, the values, the principles and the mind-set that I intend us all to adopt, going forward."