Of the eight chapters in Nader's book, the one about the Corvair is the most frequently mentioned. The 1972 US NHTSA report on it states "The handling and stability performance of the 1960-1963 Corvair does not result in an abnormal potential for loss of control or rollover and it is at least as good as the performance of some contemporary vehicles, both foreign and domestic."
Not a fan of the appeal to authority thing. They came to their own conclusion.
The rear suspension on the earlier models wasn't ideal if one had their foot to the floor going through a slalom to the grocery store, but was probably good enough for normal driving. It was identified and changed to a better design before the book was published.