Carlos Ghosn, president of Nissan Motor Co., said Tuesday that while the automaker deserves an "A or A-plus" for its rehabilitation efforts so far, its performance has yet to match all that it is capable of.

"We made a significant first step in the Nissan Revival Plan and we will continue to re-establish the credibility of the company," Ghosn, who was also appointed Nissan's chief executive officer last week, told a luncheon jointly hosted by the America-Japan Society and the American Chamber of Commerce in Japan.

Ghosn emphasized that the achievements, which included cutting the number of suppliers by 30 percent, shutting down three plants and reducing the number of workers at Nissan and its affiliates by some 14,000, were far from easy.