General Motors Co. on Thursday issued a report detailing how for 11 years it turned a blind eye to an ignition-switch problem that has been linked to at least 13 deaths but it largely pinned the blame on incompetent lower-level employees, leaving top brass untouched.

The report, which will be the subject of upcoming congressional hearings, describes shortcomings of GM engineers, including a failure to understand "how the car was built." According to the 325-page report, the highest levels of the company were not made aware.

Providing a rare peek into the operations of one of the world's biggest automotive companies, the internal investigation said GM had a long-running corporate culture in which nobody took responsibility for problems.