DETROIT (Reuters) - General Motors Co's (>> General Motors Company) management has been too slow to make changes that would improve profitability and too vague in setting near-term milestones for performance, the leader of an investor group seeking a seat on the board said on Tuesday.

"There is absolutely a lack of confidence amongst investors of the company achieving its targets," Harry Wilson told Reuters. "There's a substantial amount of shareholder frustration."

GM revealed Wilson's board aspirations earlier on Tuesday. The former member of the U.S. auto task force that helped restructure the company in bankruptcy in 2009 also plans to propose at GM's annual meeting in June that it launch an $8 billion share buyback program.

Wilson said the pace of change at GM "has been quite slow" and the No. 1 U.S. automaker was still underperforming its potential. He said GM's 2016 and 2020 profit margin targets are admirable but the company has failed to say how it will hit them.

"They put out these multi-year targets with nothing in between and it makes it hard to evaluate whether they're on track or not," he said. "As a result people really discount GM's ability to get to those long-term targets."

Wilson said GM has "way more cash than it needs, and that creates an opportunity to buy back a stock that's very cheap." He said the company would likely end 2015 with about $30 billion in cash, which suggests it will have at least $10 billion in excess cash, if not more.

Wilson, 43, called the proposal for an $8 billion buyback "incredibly conservative" and said his group, which includes David Tepper's Appaloosa Management and three other hedge funds, had wrestled with proposing a larger buyback program.

Wilson, a 1993 Harvard graduate, worked at a series of finance industry jobs, including stints at Goldman Sachs (>> Goldman Sachs Group Inc), the Blackstone Group (>> The Blackstone Group L.P.) and Silver Point Capital, an investment fund, before being tapped to join the Obama administration task force assembled to restructure GM and the former Chrysler Group LLC in 2009.

At GM, Wilson was one of the key architects of the government-led restructuring that resulted in the closure of hundreds of U.S. dealerships, the winding down of the storied Pontiac brand and a financial recapitalization that transformed much of GM’s debt into equity held by the U.S. government. The Treasury Department said in April 2014 that it lost $11.2 billion on its investments in GM.

After leaving the auto task force, Wilson ran as a Republican for comptroller of the state of New York, but lost the race. In 2011, he founded Maeva Group, and has worked on restructurings at several other companies.

He cited his experiences as an independent director at automotive technology supplier Visteon Corp (>> Visteon Corp) as a potential template for how he would work on GM's board. Visteon put Wilson on its board in 2011 at the urging of shareholders dissatisfied with the company’s performance.

"There was not enough focus on goals and milestones," he said. Since the summer of 2012, he says, Visteon’s stock has more than tripled.

(Editing by Matthew Lewis)

By Ben Klayman and Joe White