GM sales rose 8.9 per cent to 4.536 million units in the half-year ended June 30, the carmaker reported.
That compares with 4.13 million units at second-ranked Volkswagen and 3.71 million units for Toyota, including its luxury Lexus brand and affiliates Daihatsu and Hino Motors, according to statements by the companies.
Toyota's output slumped 23 per cent to 3.37 million units in the half-year after the company halted production following the magnitude-9 quake and tsunami in March.
Toyota expects production to fully recover beginning next month, one month earlier than previously announced, it said.
"Even if Toyota recovers production, it will take another few more months for sales to actually recover" as it takes time to deliver vehicles to dealers, said Takeshi Miyao, an analyst at consulting company Carnorama in Tokyo.