McLaren CEO Zak Brown says he is encouraged by the progress his team’s Formula 1 engine supplier Renault claims it has made over the winter. 

Renault says it is "very optimistic" about the gains it has made with its latest F1 power unit, with last year's leading midfield outfit confident about closing the gap to the leading trio of Mercedes, Ferrari and Red Bull in the upcoming 2019 season. 

Brown said he trusts the “encouraging” gains Renault has spoken of prior to the new campaign as he believes the French manufacturer has been “very honest” in its relationship with McLaren so far.

“We’re up to speed with the comments they’ve made and they’ve shared with us the gains they’ve made, so that’s encouraging,” Brown explained. 

“Renault are saying things differently this year than they did last year. Last year they were very grounded in where they thought their engine was its deficit to the front. 

“So on the basis of that we’ve found them to be very honest in their communication of where they think they are, so it’s encouraging they’re as positive as they are."

McLaren switched to Renault engines last year after enduring a disastrous partnership with Honda, and the Woking squad subsequently improved to sixth place in the constructors’ championship despite being hampered by a poor car design. 

“We’ve done a better job working closely with them to develop the car around the power unit, we know the power unit better - that was some of our issues last year,” Brown added. 

“We made the decision to change [from Honda in 2017] a little bit late and we had reliability issues, some of those were car design and not knowing the power unit and how to package it as well as we could do. 

“So it seems like they are in a better spot, a better position to capitalise on a year’s experience.”

Sporting director Gil de Ferran hopes McLaren will continue to make strides in 2019 thanks to its ever-improving relationship with Renault. 

"Our relationship with Renault has been consistently improving over time," he said.

"Last year was the first year for the team with Renault, and as you work together and understand how each party works, from the inside out, your relationship naturally improves.

"You get to know each other better, the conversations get easier and by consequence the technical collaboration tends to improve.

"The systems that you set in place, you need to run them for a while to understand the weaknesses and where to improve. I really see more of that going on than anything transformational."