DETROIT (AP) — August was a strong month for U.S. auto sales but Hurricane Harvey is putting pressure on some of those gains.

General Motors said its sales rose 7.5 percent over last August, while Toyota's were up 7 percent and Volkswagen's rose 9 percent. GM said sales of its small SUVs, including the new GMC Acadia and Chevrolet Equinox, jumped 47 percent. Toyota and Volkswagen also had strong SUV sales.

But not everyone got a boost. Nissan's sales dropped 13 percent and Fiat Chrysler's sales were down 11 percent. Ford's sales dropped 2 percent.

Other automakers report sales later Friday.

U.S. auto sales were initially expected to increase slightly in August compared with a year ago, but analysts say lower sales in the Houston area could erase at least some of those gains. Harvey likely cut U.S. sales of new cars and trucks by 1.3 percent, or 20,000 vehicles, in August, forecasting firm LMC Automotive said. The Houston metro area is the ninth-largest vehicle market in the nation.

Until last Saturday, August was shaping up to be a strong month at the eight Bayway Auto Group dealerships that Darryl Wischnewsky owns in the Houston metro area. Then came Harvey. None of Wischnewsky's dealerships suffered flooding or other damage in the storm, but he says other dealers up and down the freeways he has driven have lost all of their inventory and their buildings have been damaged.

His group, which includes Lincoln, Chevrolet, Fiat Chrysler, Volkswagen and Volvo dealers, shut down last Saturday as the storm approached and just started reopening on Thursday. Losing the Saturday alone probably cost 60 to 70 sales, Wischnewski said.

"Just that one day in Houston, that's thousands of cars," he said. "I think it will probably affect the national numbers as well."

Now service is busy, but buyers are few as people try to recover from the massive rainfall, so the Labor Day weekend is likely to be slow.

Sales are expected to pick up in September and October as people replace cars destroyed by floods. Black Book, a service that determines used car prices for dealerships, estimates total losses of 500,000 to 1 million cars in the Houston area due to Harvey's rainfall. Vehicles also were damaged at around 500 dealers, the service said.

For August, automakers said:

— Nissan Motor Co.'s sales fell 13 percent to 108,326. Luxury Infiniti sales grew as that brand introduced new models, including the QX30 SUV. But Nissan brand sales fell 15 percent.

— General Motors Co. said its sales jumped 7.5 percent to 275,552. SUV sales were strong, as new SUVs like the GMC Terrain arrive in dealerships and dealers offer good deals on old ones. GM also said its sales to rental car fleets rose 29 percent to 7,600 vehicles. But August was an anomaly; GM said it's still on track to cut low-profit rental car sales by 50,000 vehicles this year.

— Toyota Motor Co. said its sales rose 7 percent to 227,625. Toyota's car sales dropped 7 percent, but its SUV and truck sales jumped 19 percent thanks in part to strong sales of the RAV4 small SUV.

— Ford Motor Co. said its sales fell 2 percent to 209,897. Ford sold more than 77,000 F-Series pickups in August, a 15 percent gain over last August. But its SUV and car sales were down.

— Fiat Chrysler's sales fell 11 percent to 176,033. Sales of some individual models, like the Jeep Grand Cherokee and Dodge Caravan, saw strong growth, but sales of the company's best-seller, the Ram pickup, dropped 7 percent.

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AP Auto Writer Tom Krisher contributed from Detroit.