The rebound by Toyota and Honda brought the question of incentives to center stage.
When the March 2011 earthquake led to bare Toyota and Honda lots in May, competitors took it as a signal to throttle back on incentives.
Now all the Japanese are fully stocked. Toyota Motor Sales U.S.A. rose 87 percent from May 2011, and Toyota/Scion, up 89 percent, passed Chevrolet and was second only to Ford among brands.
American Honda, which struggled in April, was riding high in May. Sales were up 48 percent after a 2 percent decline the month before.
"Honda's return to strength is in full swing," said John Mendel, American Honda's top sales executive.
He said it was the best May for Honda/Acura since before Lehman Bros. collapsed in the fall of 2008, sparking a financial crisis. Honda Division reported sales of 119,411, a 46 percent increase as sales of the Civic surged 83 percent.
"The Civic, which received much media scrutiny when launched, had one of its best sales months in recent history," said Edmunds.com analyst Jessica Caldwell.
At Toyota Division, fleet sales have begun to decline as a percentage of total sales. It was 15 percent through April, then dropped to 13 percent in May. And it will go lower.
May was "the last month fulfilling our commitments to fleet customers," said Toyota Division chief Bob Carter. "During June, July and August, total fleet volumes will be below 8 percent, and we will be in single digits for the rest of the year."
He said Toyota intends to "stay aggressive" with marketing efforts in June, including 0 percent financing on many models. The Camry will have 2.9 percent financing and a $219 monthly lease deal in much of the country.