Honda Motor Co. appears to be the biggest beneficiary of a steep drop in sales this month of Toyota Motor Corp. vehicles, according to a study by auto research firm TrueCar.com, The Detroit News reported.

Toyota's retail market share has slumped more than five points to 12.1 percent in mid-February from 17.5 percent on Jan. 21, when the Japanese automaker issued its second big U.S. recall. Toyota has recalled more than 6 million vehicles in the United States since November, mostly for acceleration-related issues.

Honda's U.S. market share increased 1.8 points to 13 percent during that period, and Ford Motor Co. recorded the second-highest gain of 1.1 points to 11.7 percent.

Retail sales refer to auto sales to individuals through dealers and exclude fleet and car rental company purchases. Retail sales tend to be the most profitable for car companies.

If the trends hold for the rest of the month, Honda will emerge as the automaker with the highest retail market share in the United States, according to TrueCar. Honda does very little fleet business.

Its gains might seem surprising, as Honda was among the few car companies that didn't offer incentives to customers trading in Toyotas.

But TrueCar analyst Jesse Toprak said he wasn't surprised. "The most cross-shopped brand for Toyota is Honda, and has been for a long time," he said.

Chevrolet's market share slipped despite General Motors Co.'s aggressive marketing and incentives, according to TrueCar.

"If someone isn't going to buy a domestic vehicle, $1,000 isn't going to convince them," Toprak said. "Ford benefitted because of its improving image and quality, not necessarily because they offered an incentive."