SOUTHFIELD, Mich. - Detroit's three carmakers all reported surprisingly robust August sales, powered by pickups and sport utility vehicles, suggesting U.S. consumers are undeterred by the marked decline in global stock markets.

Ford and Fiat Chrysler Automobiles reported surprising sales increases, while General Motors Co. posted a small decline, after cutting back low-margin sales to rental fleets. But GM executives boosted their full-year outlook for the market by 300,000 vehicles.

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America's love affair with new trucks shows that the economy is still a standout as Europe's recovery ambles along and China is slowing. Not even a 6.6 percent drop in the Dow Jones Industrial Average last month has kept consumers from dealerships. Auto stocks fell much less on Tuesday than those of other sectors.

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"The market is down but consumers don't seem to care, they seemed to shrug it off," said Jeff Schuster, senior vice president of forecasting for research firm LMC Automotive in Troy, Michigan. "If the market stabilizes we should have a really robust September."

GM's 0.7 percent decline beat analysts' forecast, leading the company to say that sales this year may reach 17.3 million, up from an original forecast of as many as 17 million cars and light trucks. The Detroit-based automaker projected a 17.5 million annualized selling rate for August. Analysts had estimated the pace would be 17.3 million.

Ford's light-vehicle deliveries increased 5.6 percent and Fiat Chrysler's rose 1.7 percent. Both were projected to report decreases.

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Fiat Chrysler's North American unit sold 201,672 vehicles in the United States last month, the second time this year that the group topped 200,000. Analysts had predicted a 1.2 percent decline, the average of eight estimates compiled by Bloomberg. Projections ranged from a drop of 3.7 percent to an increase of 0.8 percent. Eight models, including four Jeeps, had their best August ever.

"In spite of a tough 2014 comparison and extreme stock market volatility, our dealers' competitive spirit kicked in and propelled us to our 65th consecutive month of year-over-year sales increases," Reid Bigland, head of sales for the unit formerly known as Chrysler, said in a statement Tuesday.

Chrysler exited bankruptcy in 2009 with a new leader and sales momentum that hasn't let up for more than five years. Deliveries of Ram pickups and Jeep sport utility vehicles helped sustain the streak in August, even as Labor Day weekend sales were pushed into September. Analysts estimated that Ford's sales declined 0.2 percent

All major automakers were projected to report declines for August. The industry was projected to post a 3.3 percent decline in August deliveries of cars and light trucks to about 1.53 million, the average of five analyst estimates in a Bloomberg survey. There were 26 selling days last month, one fewer than in August 2014.

A messy calendar and a choppy stretch on stock markets won't alter what's been driving auto sales in 2015 to the highest levels in at least a decade, said Karl Brauer, senior analyst at Irvine, California-based Kelley Blue Book. Unemployment is down, as are interest rates and fuel prices. The average of 12 analyst estimates is for a 17.3 million light- vehicle selling rate, adjusted for seasonal trends, for August, the same as a year earlier.

Fiat Chrysler forecast a 17.8 million selling pace for the month, including medium and heavy trucks that typically account for at least 200,000 deliveries.

"All the fundamentals that drive vehicle purchases are still relatively strong if not exceptionally strong," Brauer said. "Nothing's changed. The calendar can swing sales one direction based on a holiday. Last year August looked great and September got short shrift and this year August is taking the hit."

Consumers typically flock to dealer lots on Labor Day weekend, the traditional end of summer, as the model year is changing over. They're drawn by new designs or discounts on outgoing vehicles. Last year, the weekend made up a fifth of August's sales, according to J.D. Power. That surge led to the most sales in any August since 2003, TrueCar Inc. said.

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Since Chrysler's bankruptcy, Bigland has benefited from a growing U.S. market that rebounded from 10.4 million vehicles sold in 2009 to an almost 17 million pace this year. At the same time, Chief Executive Officer Sergio Marchionne has expanded the Jeep lineup, split off Ram trucks as its own brand, added Fiat and Maserati to the family and improved the car lineup with the Dodge Dart and Chrysler 200.

"FCA accomplished something that nobody would have predicted a few years ago -- to have five-plus years of sales increases -- even in an accelerating market," Brauer said. "It's an impressive feat and reflects very well on Sergio."

Toyota may have led the August decliners, with analysts estimating a 10 percent drop, followed by Volkswagen's VW and Audi brands, which may see a combined 7.5 percent decrease, and a 7 percent projected slide for Honda Motor Co.

Deliveries for GM, which reduced sales to rental-car companies 38 percent in August, had a narrower drop than the 2.6 percent projected by analysts. Sales of GM's Chevrolet Silverado pickup rose 12 percent while GMC Sierra pickup deliveries increased 7 percent.

Ford sold 71,332 F-Series pickups last month, an improvement of 4.7 percent from a year earlier and the first time the truck line, featuring an aluminum-bodied F-150, crested 70,000 in a month this year. The Dearborn, Michigan-based company is offering 72-month, no-interest loans on Ford brand vehicles.

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Ford's car sales dropped 7 percent, led by a 37 percent drop-off in the C-Max hybrid and a 26 percent decline in the Focus compact. SUV sales rose 12 percent, led by a 79 percent gain in the big Lincoln Navigator and a 36 percent rise in Edge deliveries.

One possible deterrent for shoppers could be the turbulent stock markets. When consumers feel their savings are at risk, they often pull back on large and discretionary purchases. So far, that hasn't been the case, said analysts such as Schuster.

Analysts were much more focused on how the calendar would influence the month's results.

This is the first time since 2012 that Labor Day weekend sales will be counted for September, J.D. Power said. This year, the holiday falls on Sept. 7. Last year, it was on Sept. 1.

This August wasn't Fiat Chrysler's first close call. The company reported gains of 1.7 percent for March 2015 and 0.7 percent for September 2013, when the average estimate was for a 2.8 percent decline.

Shares in the Italian-American automaker, which is based in London, rose 22 percent this year through Monday, more than any U.S. automaker, including Tesla Motors Inc., which gained 12 percent.

The company's Auburn Hills, Michigan-based FCA US unit remains the most dependent on truck sales of any full-line automaker in the U.S. market, which has worked well in 2015. The parent company raised its full-year earnings forecast in July on the strength of the Jeep brand.

"Our trucks and Jeeps are selling well, but it has been difficult selling the car lines -- and we have cash-back on them," said Jim Hardick, managing partner of Moritz Dealerships, which owns Chevrolet, Kia and Chrysler-Jeep-Dodge- Ram outlets in Fort Worth, Texas.