DETROIT, Aug. 3 - Auto sales rebounded in July after a disappointing June, driven by hot products like the Toyota Sienna minivan and the Chrysler 300C sedan and by big incentives on sport utility vehicles, figures released on Tuesday showed.

Ward's AutoInfoBank estimated that July's seasonally adjusted selling rate was 17.24 million units, a sharp increase from the 15.4 million-unit rate in June, the lowest in six years.

The General Motors Corporation, which suffered from double-digit declines in June, said that it had its best sales month for the year last month as it pushed aggressively to reduce the high inventories it had at the end of June. But its sales still fell compared with those in the month a year earlier, when G.M. had record sales that pushed its market share for the month up to 30 percent. G.M.'s sales were down 3.62 percent, to 455,156 cars and trucks, compared with sales in July 2003, according to Ward's.

G.M.'s chief sales analyst, Paul Ballew, said the company's market share for light vehicles reached 29 percent last month.

Mr. Ballew said the company would keep up the pressure to reduce its inventories, which are still at 1.15 million units, or about a 70-day selling rate. The industry average is a supply of about 67 days of cars, and Toyota and some other automakers are closer to a 30-day supply.

G.M. already announced that this month that it would add $500 to $1,500 in cash incentives for customers who finance their purchases through the company's finance unit, the General Motors Acceptance Corporation, or G.M.A.C. Those come on top of incentives that have exceeded $5,000 for the company's large sport utility vehicles.

"Our strategy going forward is to improve upon the basics and stay aggressive and competitive," Mr. Ballew said in a conference call to discuss the company's sales. "It's a bit of hand-to-hand combat out there."

But some in the industry are starting to believe that incentives are having less of an effect on consumers. "Zero-percent interest has become standard equipment on vehicles, like windshield wipers," said George Pipas, chief sales analyst for the Ford Motor Company. "Raising incentive levels more is throwing good money after bad."

Ford sales, which also suffered in June, fell 8 percent in July, to 279,443. But Mr. Pipas said the company had reduced its higher-than-normal inventories, ending the month with 786,000 units, or a supply of approximately 79 days. Ford's market share was 18 percent in July.

The Chrysler division of DaimlerChrysler was once again the strongest domestic player, with a 2 percent increase in sales, led by strong sales of the 300C and a 21 percent increase in sales of the Dodge Durango.

Each represents a trend driving auto sales - popular products and good bargains.

The 300C has captured the imagination of consumers with its striking grille and "Bentley-esque" design. Chrysler has sold 53,708 units this year with hardly any incentives.

The Durango, on the other hand, has a $4,000 cash incentive and a $1,000 bonus if customers finance it through Chrysler's financial unit. "It's not unexpected to see incentives like this on high-margin vehicles," said Gary Dilts, Chrysler Group's senior vice president for sales.

In fact, sport utilities now carry some of the highest incentives of any vehicle, making it difficult for automakers who resist them.

While G.M. put big incentives on all its sport utility vehicles and posted big increases - sales were up 11 percent, to 137,181 units, in July - sales of Toyota's full-size Sequoia were down 22 percent.

"We don't put incentives on the Sequoia," said Sam Bhutto, a Toyota spokesman. But he said the company did put incentives on the Tundra full-size pickup, which saw a 23 percent rise in sales.

Despite the Sequoia's stumble, Toyota's overall sales reached record levels, up 13.7 percent to 200,206.

With 12.9 percent of the market, Toyota is close to the 13.44 percent market share held by DaimlerChrysler's United States operations, which include Mercedes-Benz.

But without Mercedes, Toyota outsold Chrysler for the first time this year by more than 10,000 units. Last August, Toyota, including its Lexus luxury division, outsold Chrysler - minus Mercedes - for the first time.

Toyota, in particular, has been making inroads with consumers concerned about high gasoline prices, which are hovering around $1.88 a gallon on average.

Most automakers say that higher gas prices have not affected sales. G.M. said that sales of its Hummer sport utility vehicle had their best month ever this year.

But Toyota has stressed in an advertising campaign that it has several models that get more than 30 miles per gallon. The company also has a months-long waiting list for its Prius hybrid, which runs off electricity and gasoline.

Toyota is not the only Japanese brand that is making major inroads into the United States market. Nissan's sales surged 30.9 percent in July, to 93,321 units, giving it a 6 percent market share.

The company said sales of its new Titan full-size pickup were also gaining momentum. In July, the company said, it sold 8,726 units, an increase of more than 1,000 trucks from June, putting it on track to sell about 100,000 units at year's end.

That is still small compared with the likes of the best-selling Ford F-Series, which sold more than 80,000 units last month. But Nissan's truck entry is yet another indicator of how aggressive the Japanese brands have been in moving into segments once considered off limits to anyone but United States automakers.