McLaren has made an exploratory approach to Mercedes about an engine supply, according to the BBC.
McLaren endured a problematic pre-season with its Honda power unit, which was plagued with reliability issues and was lacking performance compared to its rivals. A frustrated Fernando Alonso, whose contract with McLaren expires at the end of 2017, labelled Honda the team's "only problem" coming into the new season and said it was missing 30km/h of speed on the straights alone.
Honda has since downplayed its chances of rectifying its performance deficit in time for the Australian Grand Prix on March 26, leading to questions about Alonso's future and whether McLaren should look for a new supplier. According to the BBC, McLaren has approached the reigning world champions, who supplied them engines before they switched to Honda in 2015, about the possibility of a future deal.
The report said McLaren is "evaluating options" in the event its relationship with Honda cannot be made to work. Earlier this week, team boss Eric Boullier conceded the team would be in a much better position with its old engine partner.
Asked if the team would be winning "right now" with a Mercedes engine inside the MCL32, Boullier told Spain's AS newspaper: "Yes, we'd be winning again."
A return to Mercedes would be ironic given former McLaren chief Ron Dennis' assertion that it is impossible in modern F1 to win a championship as a customer team, something which motivated the switch from Mercedes to Honda power in the first place. The reforming of that partnership has fallen well short of rekindling the iconic success of the late 1980s and early 1990s, finishing ninth in 2015 and sixth in 2016.
The removal of the restrictive engine token system, which limited the amount of changes that could be made to an engine during an active campaign, was seen as the perfect opportunity for Honda to rise back to the top in 2017 after starting the V6 turbo era a year later than its rivals. However, F1 boss Yusuke Hasegawa has admitted he was surprised by the performance of rivals Mercedes and Ferrari in winter testing.
McLaren is wary of another poor season impacting its ongoing search for a title sponsor, which executive director Zak Brown hopes to secure by 2018, but it is also mindful of Alonso's contract situation. Though the two-time world champion is not going to consider his future until the summer break, Boullier believes the only hope McLaren has of keeping the Spaniard is to deliver a competitive car to him this season.