General Motors, Ford Motor Co and Chrysler Group all finished ahead of Toyota, and Korean powerhouse Hyundai Group was less than 1000 vehicles away from bumping its Japanese rival down to fifth.
Toyota delivered 108,387 new vehicles last month, which was down a considerable 33 percent compared with the same month in 2010 when it sold 162,813 cars, SUVs and trucks.
The good news for Toyota is that it expects to increase production output to 90 percent of planned levels during June, which is well ahead of schedule and should ease the pressure on inventory-poor dealers.
Toyota was not the only Japanese brand to be hit hard in May, with Honda (down 23 percent), Mazda (down 21 percent), Subaru (down 15 percent) and Nissan (down nine percent) all slipping from their 2010 results.
Suzuki (up 20 percent) and Mitsubishi (up 60 percent) were the only two Japanese manufacturers to reverse the trend.
Meanwhile, the Detroit Three continue to enjoy a sales rebound in 2011 and filled the podium for the first time in years.
GM led the way with 221,192 vehicles sold, followed by Ford on 191,529 and Chrysler with 115,363.
Year-to-date in 2011, Chrysler is up 20 percent compared with 2010, GM is up 19 percent, and Ford is nine percent ahead of last year.
Toyota had been tracking in positive territory but is now one percent behind its position in 2010.
Strong performers after five months of 2011 include BMW Group (up 19 percent), Hyundai Group (up 35 percent) and Volkswagen (up 19 percent).