March was a solid sales month for most Japanese automakers in the United States, but the impact of the massive quake in Japan is likely to weigh on their sales later this month and in May.

Bob Carter, a senior manager at Toyota Motor Sales USA, said the North American operations were "somewhat insulated" in March from the disruption in the parts-supply industry in Japan, reported The Detroit News.

About 70 percent of the vehicles Toyota sells in the United States are built at its North American plants, which are all running, unlike the Japanese plants.

But Toyota and Honda Motor Co. recently said stoppages were likely at their North American factories because of shortages of crucial parts shipped from Japan.

"We know there will be challenges in the coming months as we continue to deal with supply chain issues," said John Mendel, executive vice president of sales for American Honda.

Nissan Motor Co. said Friday that it would suspend production at several North American plants for a few days this month.

It will halt output at its Canton, Miss., factory, and at its Smyrna and Decherd plants in Tennessee on April 8, 11 and 18 through 21. Production will be stopped at the Cuernavaca facility in Mexico this week and in Aguascalientes during the week of April 11.

Jesse Toprak, analyst at pricing specialist TrueCar.com, said Japanese automakers still have plentiful inventories of most, though not all, vehicles.

"There are going to be shortages of vehicles made solely in Japan," such as the Toyota Prius, he said. Toyota has an 18-day supply of the popular hybrid.

But "the impact in April is not going to be dramatic," he said. "There'll be more of an impact in late April and May."

The leading beneficiaries of the Japanese automakers' misfortunes are likely to be Detroit's automakers, Hyundai Motor Co. and Germany's Volkswagen AG.

South Korea's Hyundai has a lineup of fuel efficient and quality cars that compete directly against the Japanese brands, and it doesn't rely heavily on Japanese components in its manufacturing process. "By far, Hyundai's going to be the biggest beneficiary," Toprak said.

General Motors Co. and Ford Motor Co., which have a competitive lineup of fuel-efficient cars, are expected to benefit, investment firm Deutsche Bank said in a research note Friday.

"Their market shares are likely to rise as Japanese (automakers') inventories fall," it said.