Jenson Button conducted a safety inspection of Fernando Alonso’s McLaren after the Spaniard’s crash in testing in Barcelona last month before deciding to climb into the car himself, at the following test session also at the Circuit de Catalunya.

As he prepares for Sunday’s Australian Grand Prix, a race he has won three times in six years, Button said: “I will not get into a car unless I am 100% sure it is safe. I spent hours going through the data with the engineers and talking to them about the incident. I trust these guys and that is why I have the confidence to drive it this weekend.

“I needed to know that before getting into the car at the next test so I made sure of it. When you are driving a Formula One car at the limit you need to be sure.”

Alonso suffered concussion after his crash and was detained in hospital for three days, pulling out of the opening race in Melbourne. The reasons why he drove into a wall are still unknown but Button said: “There was nothing wrong with the car whatsoever and he did not, as far as I’m aware, get an electric shock. Everything is working correctly. The engineers have got every test under the sun to understand steering loads and everything involving the car.”

Button said after Alonso’s crash that the data from the car looked strange. “Of course it looks strange, he hit a wall,” he said. “It’s not a normal racing line around Turn 3 in Barcelona, so yeah it looks strange.” Asked whether he thought it was a normal accident Button shrugged and added: “I can’t comment on that. It’s unfair.”

After their reliability issues during the testing season, Button believes McLaren will not be competitive for some time into the new season. “We definitely won’t be fighting for a win here,” the 35-year-old conceded. “The important thing for us is to see improvements every race and progress. The power unit package is so tight and so advanced that you do have issues and we have had more issues than we would have liked. The reason it is so tightly packaged is for the air flow over the rear wing, so it really shows how closely McLaren and Honda have been working together.

“It’s great but you do have problems. We have to hope those problems are behind us and we can put as many laps as we can under our belts this weekend. Whether we score points or not is irrelevant, it is all about improvements race to race. I would rather not score points here and then win a race later in the year.”

Button’s seat at McLaren for 2015 was not confirmed until the end of last year and in light of Alonso’s absence his experience could prove crucial, particular given the team’s troubles in testing and the fact Alonso’s replacement is the inexperienced Kevin Magnussen. “We are a year behind the other manufacturers and the design is more aggressive,” said Button. “The design of the power unit needed to be aggressive and to be a challenge to Mercedes in the future.

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“Honda are the manufacturer who will take it to Mercedes in the future. There are going to be teething problems but it is about answering those issues right now.”

Asked if his drive this year feels like a bonus, Button added: “No. This is where I should have been. It doesn’t feel like a bonus, it feels normal, right.”