DETROIT (Reuters) - General Motors Co (>> General Motors Company) shareholders on Tuesday elected all of the automaker's board nominees, overwhelmingly rejecting a slate proposed by hedge fund Greenlight Capital and handing a major defeat to billionaire investor David Einhorn's bid to split the company's shares.

Preliminary results showed more than 91 percent of shareholders voted against Greenlight's proposal to have GM offer dividend and capital appreciation shares, according to GM officials at the automaker's annual shareholders' meeting.

GM's nominees were elected with between 84 percent and 99 percent of the vote, the company said.

Greenlight founder David Einhorn floated his proposal back in March, saying it could boost the automaker's $52 billion (£40.3 billion) market capitalisation by as much as $38 billion.

But right at the outset, rating agencies said Einhorn's plan could negatively impact the automaker's credit rating and he failed to rally other shareholders to his cause. Warren Buffett's Berkshire Hathaway Inc (>> Berkshire Hathaway Inc.) remained conspicuously silent on the proposal.

Proxy advisers Institutional Shareholder Services and Glass Lewis had also recommended GM shareholders vote for the automaker's board nominees and against the dual-class proposal.

Einhorn made his proposal as U.S. auto industry sales of new vehicles have begun to wane after a boom cycle that has lasted since 2010.

In comments prior to the shareholder meeting, GM chief executive Mary Barra acknowledged Greenlight's point on its stock price, saying "we do believe GM stock is undervalued," but reiterated the company's opposition to the hedge fund's proposal.

"After careful, thorough and objective analysis, we decided this (Greenlight's proposal) was not on the best interest of our shareholders," she said.

She added that the company will continue to focus "aggressively" on returning value to shareholders.

Barra also said despite the Trump administration's decision to withdraw from the Paris climate deal, the automaker will continue to push to reduce emissions.

GM shares were down 17 cents at $34.29.

(Reporting By Nick Carey and Joseph White; Editing by Nick Zieminski)

By Nick Carey and Joseph White