Fiat Chrysler Automobiles and Peugeot have finally tied the knot. But with investors yet to buy into the promise of 3.7 billion euros of annual savings from the creation of the world’s fourth-largest carmaker by volume, a deal may be the easy part. Peugeot boss Carlos Tavares, who will also run the new group, will have to work his integrational magic to get the market on side.

Under the terms, shareholders in the Italian-American carmaker will receive one share in the combined group for each share already owned. Investors in the French Peugeot owner will get 1.742 new shares for each PSA share. Fiat Chrysler investors will also receive a 5.5 billion euro cash dividend, while PSA will distribute a 46% stake in parts maker Faurecia, now worth some 3.2 billion euros. Robotics group Comau, which was initially meant for FCA investors, will be spun off later.

Fiat Chrysler investors are the cheerier so far. The carmaker has gained nearly 3 billion euros in market worth since before the news of the deal emerged in late October, while PSA has lost some 2 billion euros. Yet neither set of investors are giving much credit to the potential added value from the merger.

Taxed and capitalized, prospective annual savings have a present value of some 25 billion euros, according to a Breakingviews calculation which uses a 25% tax rate and subtracts 2.8 billion euros in one-off costs. But at around 41.5 billion euros, the combined market worth of the two carmakers is just 800 million euros larger than where it stood on Oct. 29, Refinitiv data shows.

True, the deal has yet to go through regulatory scrutiny. Also, both companies have pledged not to close factories, which limits management’s wiggle room in a gloomy car market. And there may be lingering concerns about a racketeering lawsuit General Motors filed in November against Fiat Chrysler, alleging it had bribed union officials.

Still, Tavares’s aim looks broadly credible. Four-fifths of savings will be realized by combining production platforms, consolidating electric vehicle investment and using scale to squeeze suppliers. The balance will come from closing duplicated back-office functions.

Analysts reckon Tavares has thus far been able to achieve most of the targeted synergies at Opel without closing plants. He might need to remind investors of his turnaround skills.