Honda’s return to Formula 1 in 2015 as a power unit supplier to McLaren has been disastrous, with the Japanese firm’s power units so far proving unreliable and lacking in performance.

As a result, McLaren on Friday finally confirmed what had been rumored for some time—that it would cease its partnership with Honda at the end of the current season.

McLaren had been under contract with Honda until 2024 but the two have managed to reach an amicable agreement.

"It is unfortunate that we must part ways with McLaren before fulfilling our ambitions, however, we made the decision with a belief that this is the best course of action for each other's future," Honda President Takahiro Hachigo said in a statement.

McLaren will switch to a Renault power unit in 2018 and the two seasons after that. By 2021, more suppliers are expected to enter due to new rules aimed at reducing the cost and complexity of power units. One of the new suppliers could end up being Porsche. There are also rumors of McLaren developing its own power unit.

2017 Renault Sport R.S.17 Formula One race car

2017 Renault Sport R.S.17 Formula One race car

In the meantime, it is expected the Renault power unit supplied to McLaren will have a parity specification to the Renault power units currently supplied to Renault’s own F1 team as well as Red Bull Racing.

In a statement, McLaren said Renault will establish a close working relationship with McLaren’s own engineers and technicians going forward. It will be the first time the two have joined forces in F1 despite both competing in the sport for decades.

The shakeup is thought to have been critical in McLaren being able to retain Fernando Alonso, whose current contract ends this season and is yet to be renewed. If Alonso does stay with McLaren, it means he will now be using power units from the team with which he scored his two world championships (2005 and 2006).

As for Honda, the firm is confirmed to be supplying Toro Rosso in 2018, so it won’t be pulling out of F1. The Red Bull feeder team is currently using Renault power units.

As part of the deal, Renault has been granted access to Toro Rosso driver Carlos Sainz as a replacement for Jolyon Palmer in 2018. Sainz will be paired with Nico Hulkenberg at Renault in the coming season. A replacement for Sainz at Toro Rosso is yet to be announced.