I would suggest that she establishes an independent ombudsman, where conscientious engineers who have been muzzled by their cost-concerned bosses can go anonymously to the ombudsman, who has a direct line to the CEO and president of GM.(Daily Intelligencer.)
She can make that happen. Look what it's costing them: It's already at $750 million and growing. What's it cost them in lost sales? All kinds of stuff spills out, even if it's not directly related to the ignition switch. She knows that it's just going to get worse and worse. There are going to be whistle-blowers, and plain envelopes, especially when the press sees prizes — they see Polk Awards, Pulitzers, and so on — once they get into that realm, there's no stopping it.
This has all the elements. It's a cocktail that gets it going. It is very difficult to get the press into that realm — take it from someone who knows from over the years.
Related post: Society of Women Engineers Magazine Article on Ombuds.