The fates of companies and thousands of jobs will depend on which strategy turns out to be right. If the market has hit bottom and begins to grow again, as some in the industry predicted on Tuesday, Opel’s decision to offer a face-lift of its flagship Insignia, a sibling of the Buick Regal, will look smart. But if sales fail to improve, the Insignia and other new models may sell only at big discounts, adding further to the billions of euros in losses that Opel has accumulated in Europe. The same risk faces other carmakers that have suffered most since European sales began to plummet in 2008, including Ford, Renault and PSA Peugeot Citroën.

Because Fiat owns Chrysler, and its chief executive, Sergio Marchionne, is chief executive of both companies, the Italian carmaker’s fate has implications for its American sibling. Mr. Marchionne, normally a dominant presence at car shows because of his bluntness and sarcastic wit, raised eyebrows when he canceled a news conference planned for Tuesday. A spokesman for Fiat said that Mr. Marchionne was too busy and that his low profile did not signal “anything sinister.”

Because of the enormous complexity of designing and making a car, including marshaling a large supplier network, decisions on when to introduce and produce new cars are made at least two years in advance. Auto executives who are unveiling cars now — or, like Fiat executives, are not — are reckoning with decisions made long ago.

Still, in the here and now there is a strong correlation between how the auto companies are assessing the near-term market and the availability of new models. Mr. di Montezemolo of Ferrari voiced pessimism about the mass market. “Europe is still very difficult,” he said. “I don’t see any kind of recovery.”

Stephen Odell, chief executive of Ford of Europe, however, said on Tuesday that he expected the European market to grow 20 percent in the next five years. “There are plenty of indicators we are running around what looks like the bottom,” he said.