An investor group demand that General Motors Co give back more of its $25 billion cash hoard confronts Chief Executive Mary Barra with a challenge to her plans for building the company and rewarding shareholders. Barra and GM’s chief financial officer Chuck Stevens have signaled they will recommend returning more of the cash once the Detroit automaker knows how much it will have to spend to resolve legal issues related to the company’s recalls of millions of cars equipped with defective ignition switches. Several shareholders contacted by Reuters said they agree with former U.S.