Suzuki Motor Corp patriarch Osamu Suzuki is stepping down as chief executive and the Japanese automaker promised to cut executive pay and slash 2015 bonuses, hoping to draw a line under the bruising admission of major flaws in its fuel tests. Executive vice president Osamu Honda, who also served as chief technical officer, will retire, taking responsibility for the research and development team at the heart of the testing scandal.

Japan’s No. 4 automaker by sales said it had used the wrong methods to calculate mileage for models going back to 2010, widening a mileage testing storm that had already rocked smaller rival Mitsubishi Motors Corp.

Suzuki, who has led the company for nearly four decades, acknowledged that during the past few years it had become difficult to oversee all of the company’s operations on his own. Suzuki, 86, will remain as chairman, but his narrower role is a recognition of responsibility for a testing error the company previously shrugged off.

The automaker used indoor tests for its cars’ individual parts, rather than testing vehicles on an outdoor course. It said this was done as its testing site is on a windy hill by the sea, making readings erratic. Suzuki, as chairman, will oversee the company’s efforts to strengthen compliance and improve training for engineers, while reworking its mileage testing procedures to ensure they comply with regulations.

The testing scandals at Suzuki and Mitsubishi come after Volkswagen AG was first discovered last year to have cheated diesel emissions tests in the United States.