Fernando Alonso can't hide his delight at finally having a 'proper' engine in the back of his MCL33, and not a prototype power unit under constant development.
McLaren split with Honda at the end of 2017 after three troubled seasons together. This year they go into battle as a Renault customer team.
"We have an engine that is not an experiment," Alonso said after the first day of pre-season testing at the Circuit de Barcelona-Catalunya.
"It's a new engine that we have to open up and see what we find out. It's an evolution from last year and has already won races."
Alonso said it was the very fact that McLaren was no longer on its own in terms of engine supply makes a huge difference. This year they can share development with Red Bull and the Renault works team.
"There are two other teams with the same engine," he explained. "If we have an issue, there are many people trying to find a solution that is positive for everyone.
"Even this morning when we had an issue with the car and we lost two hours. But there were other guys with our engine running - any information or driveability issues or deployment issues, they will face the same and find a solution.
"So maybe when you go back to the car you have the solution already thanks to them," he noted. "It is a very good position to be in and helpful."
The downside of the situation is that McLaren is also in direct competition with those same teams, and will have no where to hide.
"I see no reason why things would go badly," Alonso said. "What I don't have is any reason to believe we are not going to be competitive.
"McLaren is, if not the best, one of the best teams in this sport. Not lately, but in history.
"Therefore, seeing the chassis we had last year, I see no reason why we wouldn't be competitive this year."
So far, the team is just getting to know its new engine and isn't making too many direct comparisons with Red Bull and Renault.
"We will do it at the end of every week," he said. "We will see how many laps they did and what was the pace and consistency.
"It is difficult to know about fuel loads, etcetera, and what they are doing at different times. But there will be a benchmark there and something to look at."
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