US auto sales posted their best July performance since 2007 on Wednesday, but results were mixed as Ford and General Motors stumbled to a loss as rivals Chrysler, Toyota and Honda saw big gains.

While some analysts have expressed concern that the weakening economy and rising gas prices could impact sales, automakers expressed confidence that demand would remain strong.

Total industry sales rose 8.9 percent from July 2011 and came in at an adjusted, annualized rate of 14.09 million vehicles, according to Autodata.

That's up from 14.08 million in June but down sharply from the year's peak pace of 15.1 million in February.

"We are anticipating that the momentum generated through the first six or seven months will continue," Toyota division head Bill Fay said in a conference call.

Toyota has maintained its forecast for 2012 sales of 14.3 million vehicles, Fay said, noting that the sales pace has topped 14 million in all but one month so far this year.

"Signs of a housing recovery and good news on consumer confidence and household income should help keep the light vehicle selling rate in the 14 million range and drive seasonally higher truck sales as we move toward fall," said Kurt McNeil, head of GM's US sales operations.

Ford said it still expected total industry sales to come in at 14.5 to 15 million vehicles this year but cautioned that given the recent slowdown, it will likely be close to the bottom of that range.

"We think the retail market is still holding up relatively well," Ford sales analyst Erich Merkle said in a conference call.

Though economic uncertainty could dampen consumer confidence, auto sales are expected to continue to drive growth, said Lacey Plache, an economist with automotive site Edmunds.com.

"The bottom line is that pent-up demand for autos is still strong and can be expected to continue to contribute sales, given the aging fleet and the current expansion of credit," Plache said.

July's results were somewhat skewed because they were being compared to a period last year when Toyota and Honda saw their inventories shattered by supply shortages in the wake of the devastating Japanese quake and tsunami.

Other automakers also had supply shortages, but many were able to expand market share as consumers sought alternatives to vehicles with long wait lists.

Toyota's sales jumped 26 percent to 164,898 vehicles, while Honda posted a 45 percent gain from a year earlier to 116,944 vehicles.

"As our sales momentum continues to build through the summer, Honda is experiencing its best year-to-date sales in four years," said John Mendel, head of sales for American Honda.

"With success growing along with inventory, it's wonderful to once again be able to meet the strong retail customer demand for our great Honda products."

Nissan, which was not as severely impacted by the parts shortages last year, saw July sales rise 16 percent to 98,341 vehicles.

Chrysler celebrated that it has now reported sales gains for 28 straight months, as July sales rose 13 percent to 126,089 vehicles.

"July was another solid month for Chrysler Group as we again demonstrated our disciplined and methodical approach to growing sales and profits," said Reid Bigland, head of US sales.

Ford sales fell four percent to 173,966 as low-margin fleet sales dropped 16 percent. More profitable retail sales rose two percent in July.

GM saw sales fall six percent to 201,237 vehicles as retail sales slipped three percent and fleet sales dropped 15 percent due to planned reductions in low-margin sales to rental companies.

Volkswagen, which is aggressively expanding in the United States, posted a 27 percent jump in sales to 37,014 vehicles. It was the German automaker's best July since 1973.

"We're pleased to see consumers embracing our strong lineup of award-winning, fuel-efficient, high-quality vehicles and we expect our growth to continue," said Jonathan Browning, chief of Volkswagen Group of America.