DaimlerChrysler chose Valentine’s Day to raise the prospect of a divorce between its successful German division and its embattled US side after nine not altogether happy years together.

Cross the Atlantic and observers are wondering whether the tie-up between Renault and Nissan is as heavenly as previously thought after Nissan, the original ailing part of the duo, took a turn for the worse again in the last figures.

And that is not the only parallel. Both chief executives — Dieter Zetsche, of DaimlerChrysler, and Carlos Ghosn, of Renault-Nissan — are credited as turnaround kings. That means that their reputations are on the line. And so, to some degree, is the rationale of large-scale automotive mergers.

Perhaps the divorce lawyers are premature. Some industry experts say mergers can take a long time to bed in. Peugeot-Citroën believes that it took it a decade to merge properly, though its two parts were in the same country and served the same market.

The DaimlerChrysler partners have never seemed as well suited. The marriage of a luxury German brand and a US volume producer was never going to be easy or really make a lot of industrial sense. Sharing of parts and production between the two divisions has been limited by fears in Germany that the luxury marque would be sullied by links with mass production. They probably had reason. Jaguar’s X-type has never shaken off disparaging comparisons with the Ford Mondeo, with which it shares a platform.

However, Renault and Nissan inhabit the same market sector and analysts consider Nissan in better financial shape than Chrysler despite a fall of 23 per cent in its last quarterly sales. Mr Ghosn’s marriage, begun in 1999 when Renault took a controlling stake in the Japanese company, may prove to be enduring.

Elsewhere in the motor industry, joint ventures and stakeholding are becoming more common for carmakers to share costs and gain exposure to new markets without risking all in a fickle, fashion-driven market. Such will be DaimlerChrysler’s route if it stops short of full divorce and opts instead to sell part of the US business.

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