In a survey published this year by Ernst & Young of 400 executives and managers at large companies, 66 percent of respondents said companies with women on their boards achieve better financial results. Sixty-five percent said companies with women in senior leadership roles perform better.
But with few exceptions, the auto industry is behind the curve in this area. Among all companies on the Standard & Poor's 1500 index, women accounted for 16 percent of the board seats, up from 11 percent in 2006, according to a study by Ernst & Young.
"It is edging up, but not quickly enough," said Ruby Sharma, principal at Ernst & Young's Center for Board Matters.
Whereas bankruptcy transformed GM's board of directors -- before bankruptcy, the board comprised just two women and 11 men -- most companies have much less turnover on their boards, which often makes changing their makeup a slow process. And companies also don't want to lose qualified, effective board members purely in the name of demographics, Sharma said.
"When the boards are not turning over, it's very difficult to replace a particular board member with a woman," she said. "It's about a balance. You want diversity, but you also don't want to throw out the experience and institutional knowledge that a long-term board member may have."
Data from the Inforum Center for Leadership, a professional organization for women in Michigan, show that women accounted for just 14 percent of the board members selected since 2013 at the state's 18 largest public automotive-sector companies. GM added two women, while BorgWarner, Visteon Corp. and Tower each added one. Thirty other seats were filled by men.
After those additions, 19 of the 165 seats at Michigan automotive-sector companies, or 12 percent, are now women, according to Inforum's Women's Leadership Index. Again, five of those 19 are at GM.
"General Motors has absolutely broken through the barrier from tokenism to critical mass," said Terry Barclay, Inforum's CEO.
A few European automakers do have relatively diverse supervisory boards; women account for six out of 20 members at BMW, five out of 20 at Daimler AG and four out of 20 at Volkswagen AG. But Toyota Motor Corp. and Honda Motor show just one female director each in their latest annual reports, and Hyundai Motor's board is all men.
Broken down geographically, the suppliers follow a similar pattern of diversity as the automakers. At North America-based suppliers, 12 percent of directors are women, while Europe-based suppliers have boards that are 15 percent female. But women account for just 2.3 percent of directors at Asian suppliers.
Germany-based Hella KGaA Hueck & Co. has five women on its 16-member supervisory board, while Plastic Omnium and Valeo, both French, have four women on their boards. Only 13 of the 50 largest suppliers have more than one female director, and 22 companies have all men, with 12 of those based in Japan or Korea.