General Motors Company (NYSE:GM) CEO Mary Barra will testify in front of the House Committee on Energy and Commerce Subcommittee on Oversight and Investigations today and tomorrow to answer one question: why did it take so long for dangerous ignition switches to be recalled? According to the written testimony that she made available yesterday, she frankly doesn’t know. “More than a decade ago, GM embarked on a small car program. Sitting here today, I cannot tell you why it took years for a safety defect to be announced in that program, but I can tell you that we will find…