Renault SA pledged back in February to make its 20-year-old alliance with Nissan Motor Co. "irreversible," after the shocking arrest of the French carmaker's boss Carlos Ghosn on charges of financial misconduct exposed deep rifts on both sides.

That goal now looks further away than ever, with Ghosn's dramatic escape to Lebanon and his repeated denials of the charges reopening old wounds, and neither firm succeeding in bridging the political and governance divide between France and Japan.

The Financial Times reports that Nissan is ramping up contingency plans in case of a breakup — which, while financially painful and costly for both sides, shouldn't be ruled out. With Renault and Nissan under new management, and advocates of closer integration on the wane, time is running out to prove that this isn't an alliance in name only.