DETROIT (Reuters) - February U.S. auto sales, an indicator of consumer spending, fell slightly even as automakers stepped up discounting to sustain sales, major manufacturers reported on Wednesday.

Demand for cars, sport utility vehicles and pickup trucks in February dipped to an annualized pace of 17.6 million vehicles, compared with a robust 17.7 million a year earlier, according to Autodata Corp.

Shares of Detroit automakers General Motors Co GM.N, Ford Motor Co F.N and Fiat Chrysler Automobiles NV FCAU.NFCHA.MI all rose as the broader market surged more than 1 percent [.N].

However, analysts pointed to caution flags in the latest results, including discounts that hit 10 percent of the average selling price for February, according to three companies that track vehicle pricing.

“With the industry at 10 percent you are in a push market,” said Mark Wakefield, head of the North American automotive practice for consultancy AlixPartners. “This is top cycle stuff.” In a push market, manufacturers try to unload vehicles, rather than respond to the pull of consumer demand.

The challenge now for automakers is to avoid over-producing vehicles or launching a price war that could undermine profits, especially as rising interest rates make it more expensive to subsidize loans and leases, Wakefield said.

“It’s that fine balance,” he said. “How much can I push the boundary without prompting a reaction that pulls all of us down?”

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The tension surfaced in another round of sniping on Wednesday between GM and Ford over which one was more dependent on discounts to prop up pickup truck sales.

On the plus side for automakers, U.S. consumers continued buying more SUVs and pickups, which generate higher profits.

Light trucks accounted for 62 percent of light vehicle sales in February. In 2016, that split was 59.5 percent in favor of trucks and SUVs, according to Autodata Corp. Over a full year, that shift would mean roughly two assembly plants’ worth of cars had been replaced by SUVs or trucks.

February sales were mixed for the major automakers. GM beat most analysts’ expectations with a 4.2 percent gain in new vehicle sales.

Ford sales declined by 4 percent, with its F-Series pickup trucks up 9 percent, SUVs rising 6 percent but cars sliding 24 percent from a year ago, the automaker said.

Toyota Motor Corp 7203.T, No. 3 in U.S. sales volume, suffered a 7.2 percent drop as sales of the company's best-selling model, the Camry sedan, dropped 15 percent.

Fiat Chrysler Automobiles NV sales fell 10 percent, as its largest-volume Jeep SUV brand dropped 15 percent.

Nissan Motor Co 7201.T beat expectations on a 3.5 percent gain, led by a 54 percent surge for its Rogue small SUV.

Honda Motor Co 7267.THMC.N sales rose 2.6 percent, helped by its trucks and SUVs, gaining 12 percent from a year earlier.