Sergio Marchionne’s plans to propel car sales at Fiat SpA and Chrysler Group LLC to the 6 million mark he says is needed to guarantee survival may take longer to realize than the chief executive officer has predicted.

Sales will total about 4.9 million autos in 2014, 1 million less than Marchionne’s target for the year, based on the average estimate of 10 analysts surveyed by Bloomberg News, none of whom expects him to attain the goal as a slowing European economy crimps demand.

The CEO plans to combine Turin-based Fiat with the No. 3 U.S. carmaker before the end of 2014 to attain what he says is the “critical mass” required to secure long-term viability, with a forecast for 104 billion euros ($136 billion) in annual revenue then. The analysts forecast he’ll miss that goal by almost 16 billion euros, and that earnings will also fall short.

“Marchionne’s ambition for 2014 is unrealistic without an acquisition, which Fiat can’t afford as it completes the Chrysler deal,” said Hans-Peter Wodniok at Fairesearch GmbH in Kronberg, Germany, ranked No. 1 by Bloomberg among analysts who cover Fiat based on the stock’s one-year return.

The Italian company, which owns 53.5 percent of Chrysler, is seeking to be one of the five or six global carmakers that Marchionne predicts will remain in coming years, according to a presentation on Dec. 9 that ended on the Bruce Springsteen lyric: “Halfway to heaven and just a mile out of hell.”

Fiat fell as much as 2.9 percent and was trading 2.4 percent lower at 3.75 euros as of 2:49 p.m. in Milan, the poorest performance in the Bloomberg Europe Auto Index, valuing the company at 4.72 billion euros. The stock lost about half its value last year, the worst record after PSA Peugeot Citroen.

Fiat-Chrysler together ranked as the world’s seventh- largest automaker in 2010, the last year for which annual figures are available, with 3.6 million sales, putting them just ahead of Peugeot, Honda Motor Co. and SAIC Motor Corp. of China, according to data compiled by Bloomberg.

Four groups -- Toyota Motor Corp., General Motors Co., Volkswagen AG and the Renault SA-Nissan Motor Co. alliance -- had sales in excess of 6 million cars, while Hyundai Motor Co. and Ford Motor Co. were within 500,000 of that figure.

Fiat’s 6 million sales goal “seems more a slogan than a real target,” said Giuseppe Berta, economic history professor at Milan’s Bocconi University. “The only chance to get there in 2014 is by combining Fiat and Chrysler with a player in Asia, a region where the group is extremely weak.”

While Renault has succeeded in its alliance with Nissan, European carmakers generally have not done well when linking with Asian automakers.

A planned VW partnership with Suzuki Motor Corp. unraveled this year, with both sides accusing the other of not adhering to the deal. Daimler AG, then DaimlerChrysler AG, abandoned a five- year partnership with Mitsubishi Motors Corp. in 2005, after the Japanese carmaker’s losses rose following a series of recalls.

Fiat is pinning its 2014 goals on expansion in faster- growing markets and isn’t planning any acquisitions to meet its target, said a person familiar with the company’s strategy who declined to be identified because it hasn’t been openly discussed. The automaker, which will begin offering its first car built in China with joint venture partner Guangzhou Automobile Group Co. in the second half of this year, may also build a Jeep model at the plant too, the person said.

Fiat led a decline in European car sales in 2011, with deliveries through November falling 12 percent to 886,178, reducing its market share to 7 percent, European Automobile Manufacturers Association figures show. Analysts estimate that Fiat, which also owns Alfa Romeo and Ferrari, is losing 800 million euros a year in the region.

Marchionne said last month that the sovereign-debt crisis may prompt Fiat to revise its operating profit targets for 2012, though any new target should overlap with part of the existing range of 1.6 billion euros to 2 billion euros, excluding Chrysler. Fiat will present forecasts next month with its 2011 results. Marchionne expects Chrysler to post $3 billion in operating profit in 2012.

Fiat will also struggle to reach longer-term targets and may limit investment amid a possible recession in Europe, said Stuart Pearson, an analyst at Morgan Stanley in London.

The carmaker “needs a new plan to raise competitiveness,” Pearson said in a Nov. 30 note to clients, cutting his forecast for 2014 operating profit to 5.2 percent of sales, compared with a range of 7.2 percent to 8 percent given by Fiat in a four-year plan in 2010.

Jeff Schuster, senior vice president of global forecasting at LMC Automotive, said the group will sell 5.4 million vehicles in 2014, adding that a total of 5.9 million is seen only in the “outer years” of the consulting company’s predictions.

“Fiat went through a rebirth and now they’re treading water,” Schuster said. Chrysler, where 2011 sales rose 26 percent in the U.S, “actually is the part of the group that is doing better than the industry gave them credit for.”

The American carmaker, which also owns the Dodge and Jeep brands, said today its U.S. vehicle sales rose 37 percent last month, beating analyst estimates.

Marchionne is struggling to boost Fiat demand in North America, where its revival of the 500 subcompact achieved 21,380 sales through October, less than half the 50,000 target. The model, the first Fiat has sold in the region since 1983, has been available in the U.S. in March.

“I just don’t see the Fiat products being the be-all and the end-all,” said Alan Baum, principal of Baum & Associates, a consulting company in West Bloomfield, Michigan. “The 500 is cute, it’s fun, but that doesn’t sell you volume.”

Still, Marchionne reiterated the overall 2014 targets on Dec. 14 at a presentation of the new Panda subcompact near Naples, adding that the group will sell about 4.6 million vehicles in 2012, with Fiat sales “flat” at around 2.2 million cars and Chrysler’s deliveries increasing to 2.4 million from a forecast of 2 million for 2011.

The CEO hasn’t excluded the addition of another partner and said in September at the Frankfurt Motor Show that “you need to create big car groups,” adding that there is “no imminent” plan for another tie-up.

Marchionne said in April that Fiat will have to “fight for China,” where it is “showing up in the last quarter of the game,” while adding there’s still room to grow.