After two and a half seasons of underperforming, in-fighting and general disappointment, McLaren's relationship with engine supplier Honda will terminate at the end of the year. To mark their split, we have charted the troubled relationship between chassis and engine manufacturer, from hopeful optimism ahead of season one to utter despair by season three.

Honda return confirmed

McLaren and Honda's rekindled partnership started with many references to the glory days of the past. Steven Tee /McLaren-Honda via Getty Images

It seemed like a perfect match. After a steady decline as a Mercedes customer team in 2013 and 2014, McLaren was set to become a full works outfit again. What's more, the new partnership had some serious historical resonance, with the iconic McLaren-Honda's of the the late 1980s and early 1990s securing 44 wins in just five years of competition. The news was made official in May 2013 ahead of Honda's full return at the start of 2015 and both sides were full of optimism for what lay ahead.

"Like McLaren, Honda is a company with motor racing woven into the fabric of its heritage," then McLaren team principal Martin Whitmarsh said. "We're proud and thrilled to be joining forces once more to take on the world in Formula One. Whilst both companies are fully aware that we're embarking on a very demanding journey together, we're hugely committed to the success of the partnership, and we'll spend the next 18 months working together to ensure that we're fully established and competitive ahead of our first grand prix together in 2015."

Takanobu Ito, president and CEO of Honda, added: "Ever since its establishment, Honda has been a company which grows by taking on challenges in racing. Honda has a long history of advancing our technologies and nurturing our people by participating in the world's most prestigious automobile racing series. The new F1 regulations with their significant environmental focus will inspire even greater development of our own advanced technologies and this is central to our participation in F1."

Honda makes bold claims

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Towards the end of 2014, plans were put in place for Honda's new engine to make its debut at the end-of-season test in Abu Dhabi. Hopes were high and so were expectations and, at this stage, Honda F1 boss Yasuhisa Arai was doing nothing to play them down.

"I have confidence that we will match Mercedes," he said as the German manufacturer powered towards a dominant first season under the new turbo hybrid regulations. "I think that the two other engine suppliers will recover next season -- I strongly believe that. And we will be there too.

"You can only make conclusions [about 2014] when you have all the different data on the table. I can imagine that Mercedes found the perfect balance between their chassis and their power unit and that the others didn't find that balance. So we work together with McLaren as one team -- because this is the only way to go."

So far, so good...

The first test

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Huge anticipation greeted the confusingly-named MP4-29H/1X1 when it first emerged into the Abu Dhabi pit lane under Honda power. But in a sign of things to come for the McLaren-Honda partnership, electrical issues limited the mule car to just five laps over two days of testing after it stopped on track twice.

"It's obviously not what we wanted to achieve," McLaren racing director Eric Boullier said. "Our target was to run the car on track, to run all the systems, and we were not expecting here to develop anything other than trying all the systems. We didn't achieve this, so we failed on this. Yes, it's not good enough and we are not happy with that, but at least we learned things which are important to be prepared for the next one."

Yet McLaren and Honda remained optimistic, with Ron Dennis, then McLaren's CEO, saying the power unit had showed impressive performance.

"The challenge for our partner Honda is hitting dates and reliability," he said. The performance is pretty impressive but of course I can't share that with you."

And Honda was still talking about targeting wins on its return to F1 a few months later...

"The new regulation package is very very complex," Arai said. "In Abu Dhabi we did a test and got many data, and in that we were already one team as McLaren-Honda. I have a strong confidence with our partnership that we will win next year in Melbourne and start a new era."

Reality strikes

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When pre-season testing for the 2015 season finally rolled round, Honda's problems were still evident. Once again, reliability was the biggest issue while performance was hard to gauge until the car had been run in anger. Dennis remained convinced that Honda's "size zero" concept was the way to go and once again Arai was optimistic the engine would come good in time for the opening race.

"On the power unit everything is working well," Arai said. "The system itself is very good and ready to race ... I still have big ambitions. We are already fixed at hardware and software and have confirmed our final data for Melbourne. I think there is no problem."

First race lays Honda's problems bare

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A freak accident in testing meant Fernando Alonso missed the first race of the new McLaren-Honda era, but he didn't miss out on much. His replacement Kevin Magnussen didn't even make it to the grid before an engine problem sidelined his car, while Jenson Button effectively completed a test session well off the pace of the rest of the field.

"The fact that Jenson was able to finish the race was a significant step forward for the whole team," Arai said, underlining how much expectations had been altered in a short period of time. "Equally, today's performance clearly displays the task that lies ahead of us to reach our objectives of achieving full competitiveness.

"This was an important race for Kevin, and we feel deeply for him. It's a great pity that we weren't able to provide him with a driveable power unit for the race. We still need to fully investigate the source of Kevin's problem, and we won't be able to look into it until the car comes back to us and we're able to take off the engine cover."

The media turns on Honda

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After a disappointing first half to its debut season, the pressure on Honda started to ramp up at the Italian Grand Prix in September. The power unit's woeful energy deployment and poor reliability saw McLaren struggle at both Spa and Monza and on Saturday evening the British media asked Arai if he planned to apologise Button and Alonso.

"I always talk to both drivers," Arai said, slightly bemused, before responding to further demands for an apology with: "Why? Why?"

He was also grilled on a claim a few weeks earlier that the Honda engine was at least on par with Renault in terms of performance.

"I talk with other engineers at other teams so maybe it [the power] is not so different or we are better than the Renault," he said. "But I don't know the exact number."

Arai was offered little help from Boullier, who was also present at the press conference, and finished looking confused at what had just happened. Meanwhile, Honda failed to make significant improvements for the rest of the year.

Arai replaced

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As testing got underway for the 2016 season, Honda announced Arai would be leaving the F1 project and would be replaced by Yusuke Hasegawa. Under new leadership the targets were more realistic, but the performance still hadn't made the step forward both McLaren and Honda had hoped for over the winter.

"It is very difficult to tell from the test results, but I am not very optimistic about performance," Haswgawa said at the end of testing. "We were around seventh and sixth; it is not very good. It is good compared to last year, but it is not very good. So I am not satisfied with that. We have bigger targets still."

Progress ... of sorts

Improvements in the final races of 2016 proved to be a false dawn for McLaren and Honda Mark Thompson/Getty Images

Although it was still the least competitive power unit manufacturer in F1, Honda made progress in 2016 and McLaren scored points at five of the last seven rounds of the season. Speaking at the Belgian Grand Prix, the scene of Honda's humiliation a year earlier, Alonso was optimistic about the way things were going.

"I think if we look at the team 12 months ago, we were in a very different situation," he said. "We were starting last here using I think the ninth engine, we were lapped two times here last year and also in Germany and Hungary, so we've definitely made a step of minutes, not even seconds in a race total time.

"So definitely we are in a much better position. We are enjoying that and the progress is definitely very optimistic for next year as well."

A make or break year

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The pressure was on for 2017, but with an entirely reworked power unit Honda was optimistic of rising to the challenge. At the launch of the new Honda-powered MCL32 in February, Hasegawa set what seemed like a reasonable target to match Mercedes' 2016 power unit.

"Of course we are aiming to achieve the top level of the power unit, which is Mercedes at this moment," he said. "But we don't know how much power they are making now. I'm feeling we are not far behind them [where they were at end of 2016], but I think we will catch up with them by the beginning of the season."

But when testing got underway there was an overwhelming sense of de ja vu as Honda not only struggled for reliability, but also appeared to have made a step backward in performance.

"Of course we knew the performance level but we didn't know the level of the other teams, so from a comparison point of view we are a little bit scared of the situation and it's too optimistic for us to expect a very good result in Melbourne," he said. "But from a trouble point of view, of course I didn't expect such a wide variety of problems that we suffered."

Upgrade deadlines slip...

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A poor performance at the season-opening Australian Grand Prix confirmed Hasegawa's worst fears. But perhaps of more concern to McLaren was Honda's inability to offer firm dates on when it could deliver a fix.

"I cannot guarantee when we can get the power, but as soon as possible of course we will try to introduce a new specification," Hasegawa said. "But it is not a one-day job. In a month's time or two weeks' time I would like to try, but I cannot guarantee here. As soon as I can prepare that I am happy to introduce that."

McLaren's patience was clearly wearing thin and by May new McLaren executive director Zak Brown admitted he was looking at other engine options for 2018.

"We've got to work through our issues and our issues are substantial in the back of the car," Brown said. "2018 is not far away, so we are going to have to evaluate how we get to the front of the field, and as Jonathan Neale my partner in racing [and McLaren COO] has said, all options are on the table and we have to get back to the front. We're not quite sure how we are going to do that, but we are working on it."

The Honda power unit was plagued by MGU-H issues at the start of the season and putting countermeasures in place became the priority for the Japanese manufacturer, while deadlines for performance upgrades slipped by. An update known as Spec 3 was scheduled for the Canadian Grand Prix but wasn't introduced until free practice in Baku, resulting in a grid penalty for Alonso before it was raced for the first time in Austria.

Spec 4 was due at Spa, but instead Honda brought Spec 3.5 and 3.6 as it waited for its final sign-off on the full upgrade.

"We had planned to introduce 'Spec 4' here but we failed, we didn't match our schedule," Hasegawa said. "We're halfway through our upgrade so we called it 3.5 and 3.6."

Grounds for divorce

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At the Italian Grand Prix one week later, McLaren's talks with Renault became fully public and high-level meetings were held in the paddock. Over the following week the deal fell into place piece by piece, culminating in Friday's announcements in Singapore.

Less than three years after McLaren and Honda had reunited with such promise, the dream had come to an end.