Italian-US carmaker Fiat Chrysler has abruptly shelved its proposed partnership with Renault of France, thwarting the latest attempt to reshape Europe's auto sector.
Here is a look at other major deals, some of which floundered, since the 1990s.
In 1998 the German group Daimler-Benz struck a deal to fuse troubled US automaker Chrysler with its prestigious Mercedes brand. It was presented as a merger of equals, but Daimler invested $36-billion in the marriage, and ran the show from the start.
By 2005, the combination had soured. Daimler boss Juergen Schrempp stepped down and his successor, Dieter Zetsche, announced in February 2007 that Daimler would sell most of its shares in Chrysler. It did so three months later, ceding 80.1% to the US investment firm Cerberus Capital Management for €5.5-billion.
In the late 1990s the ailing Italian group Fiat, which is controlled by the Agnelli family, went looking for a partner. In 2000 it agreed to hand over 20% of its shares to US giant General Motors.
But Fiat's situation did not improve, and in February 2005 GM bailed out of the deal, paying €1.55-billion to cancel an option to buy the rest of Fiat's equity.
In mid-2009, after a financial crisis struck the West, a fitter Fiat struck a deal approved by US president Barack Obama to rescue Chrysler by starting to purchase shares in the Detroit group.
In 1999, Renault acquired a 36.8% stake in the Japanese group Nissan, which was close to bankruptcy, and also bought the Romanian brand Dacia.
Renault boss Carlos Ghosn succeeded in pulling the French and Japanese companies together and became head of both in 2005. Dacia meanwhile blossomed from a derided east European carmaker to a respected low-cost brand.
A cross-shareholding deal has put 43% of Nissan's shares in Renault's hands, while the Japanese group owns 15% of Renault.
Nissan also took a controlling stake in Japan's Mitsubishi Motors. In 2018 Renault-Nissan-Mitsubishi made around 10.8-million automobiles.
However, the imbalance in the relationship has led to serious friction, highlighted by the arrest of Ghosn in Tokyo in November for alleged financial misconduct.
In 1999, when Ford was the most profitable US automaker, it bought Sweden's venerable Volvo brand for $6.45-billion.
A few years later, however, a combination of Japanese competition and rising oil and steel prices convinced Ford that it was time to look for a new buyer.
In December 2009, it said it would sell Volvo to the Chinese group Geely for $1.8-billion.
In 2017 France's PSA, which owns the Peugeot, Citroen and DS brands, said it would buy GM's European subsidiary, which includes Opel and Vauxhall, to create the second-biggest European automaker, behind Volkswagen.
Germany's Opel, which booked its first profit in 2018 after years of losses, is accelerating its international expansion, and has said it will return to Russia after a more than three-year absence.
But along with other carmakers in Britain, Vauxhall is struggling on the back of Brexit uncertainty and a drop in demand for diesel vehicles.