GM CEO Mary Barra said more than half the 15 employees forced out were senior legal and engineering executives who failed to disclose the defect and were part of a "pattern of incompetence." Five other employees have been disciplined, she said, without identifying any of them.
The automaker said it will establish a compensation program covering those killed or seriously injured in the more than 50 accidents blamed on the switches. GM said not say how much money will be involved, but a Wall Street analyst estimated the payouts will total $1.5 billion.
Barra called the report "brutally tough and deeply troubling."
The report lays bare a company that operated in "silos," with employees who didn't share information and didn't take responsibility for problems or treat them with any urgency.
Valukas also portrayed a corporate culture in which there was heavy pressure to keep costs down, a reluctance to report problems up the chain of command, a skittishness about putting safety concerns on paper, and general bureaucratic resistance to change.
He described what was known as the "GM nod," in which "everyone nods in agreement to a proposed plan of action but then leaves the room and does nothing."
Valukas exonerated Barra and two other top executives, Mark Reuss, chief of global product development, and general counsel Michael Millikin, saying there is no evidence they knew about the problems any earlier than last December.
Since February, GM has recalled 2.6 million older-model Chevrolet Cobalts, Saturn Ions and other small cars because their ignitions can slip out of the "run" position and shut off the engine. That disables the power-assisted steering and brakes, making it difficult to control the car, and deactivates the air bags.
Trial lawyers suing the company put the death toll at more than 60.
"It's somewhat comforting to realize that they do know that some things were done incorrectly and they're aware of that. They made the appropriate measures to make sure it doesn't happen again," said Ken Rimer, whose 18-year-old stepdaughter, Natasha Weigel, was killed in a 2006 Cobalt crash in Wisconsin.
Last month, GM paid a record $35 million fine for failing to promptly report the bad ignition switches to federal highway safety regulators. Federal prosecutors are also investigating and could bring criminal charges against the automaker and some of its employees.
Deep within the company, engineers and others believed the ignition switch flaw was a "customer convenience" issue rather than a safety problem, the report said. Engineers believed that the cars could still be adequately steered when the engines shut off, and they didn't realize the air bags became disabled — even after police, academic experts and others outside GM had recognized the problem, according to the report.
Around GM, engineers were instructed not to use words like "dangerous," "defect" or "safety" when describing problems in writing, which contributed to the lack of urgency in dealing with the problem, Valukas wrote. In addition, some workers told Valukas they did not take notes at safety meetings because they believed GM lawyers didn't want a paper trail.
In 2005, according to documents supplied recently to Congress, GM failed to make a repair of the switch that would have cost just 57 cents.
In his report, Valukas said he found no evidence that any employee made "an explicit trade-off between safety and cost" in dealing with the switch. But he said there was "tremendous cost pressure" at GM at the time, and he left open the possibility that it influenced the automaker's handling of the problem.