The 57 cents is just the cost of the replacement switch. The figure does not include the labor costs involved in installing the new part.
Barra testified that the fix to the switch, if undertaken in 2007, would have cost GM about $100 million, compared with "substantially" more now.
Under questioning, she said the automaker's decision not to make the fix because of cost considerations was "disturbing" and unacceptable, and she assured members of Congress that that kind of thinking represents the old General Motors.
David Friedman, head of the National Highway Traffic Safety Administration, also testified Tuesday. He blamed GM for what he said was its failure to provide adequate information to the government.
"It's my understanding that we did not have that information," Friedman said. In one example, GM didn't tell the agency that the switches didn't meet the company's specifications, he said.
Committee members questioned Friedman about why the agency didn't investigate the cars based on the information it did have. At one point, Rep. Barton was incredulous when Friedman acknowledged that NHTSA didn't fully understand how the air bags in some of the GM cars worked.
Some current GM car owners and relatives of those who died in crashes were also in Washington seeking answers. The group attended the hearing after holding a news conference demanding action against GM and stiffer legislation.
Owners of the recalled cars can ask dealers for a loaner vehicle while waiting for the replacement part. Barra said GM has provided more than 13,000 loaners.
Barra announced at the hearing that GM has hired Kenneth Feinberg — who handled the fund for the victims of 9/11, the Boston Marathon bombing and the BP oil spill — to explore ways to compensate victims of accidents in the GM cars. It's an indication that GM is considered some kind of compensation fund for victims, although Barra stopped short of saying that.
GM shareholders are also watching Barra. GM stock is down $2.75, or 7.4 percent, since March 11 when committees in the House and Senate said they would hold hearings on the recall and word leaked out that the Justice Department was investigating the company's handling of the issue.
On Tuesday, GM stock closed down 8 cents, to $34.34, after rising as high $35.14 prior to Barra's appearance.
AP Auto Writer Dee-Ann Durbin in Detroit and Business Writer Paul Wiseman in Washington contributed to this report.