Nader's first consumer safety articles appeared in the Harvard Law Record, a student publication of Harvard Law School, but he first criticized the automobile industry in an article he wrote for The Nation in 1959 called "The Safe Car You Can't Buy."^[19] In 1965, Nader wrote Unsafe at Any Speed, a study that purported to demonstrate that many American automobiles were unsafe, especially the Chevrolet Corvair manufactured by General Motors. The Corvair had been involved in numerous accidents involving spins and rollovers, and there were over 100 lawsuits pending against GM in connection to accidents involving the popular compact car. These lawsuits provided the initial material for Nader's investigations into the safety of the car^[20] GM tried to discredit Nader, hiring private detectives to tap his phones and investigate his past, and hiring prostitutes to trap him in compromising situations.^[21][22] GM failed to uncover any wrongdoing, and never explained resorting to smear tactics instead of defending the car in the popular press, where the company had considerable corporate influence. GM's avoidance of technical journals makes more sense, as it was well known among auto engineers that the early (1960-64) Corvair's swing axle suspension handled miserably.^[23][24] Upon learning of GM's actions, Nader successfully sued the company for invasion of privacy, forced it to publicly apologize, and used much of his $284,000 net settlement to expand his consumer rights efforts. Nader's lawsuit against GM was ultimately decided by the New York Court of Appeals, whose opinion in the case expanded tort law to cover "overzealous surveillance".^[25]

Nader's advocacy of automobile safety and the publicity generated by the publication of Unsafe at Any Speed, along with concern over escalating nationwide traffic fatalities, led to the unanimous passage of the 1966 National Traffic and Motor Vehicle Safety Act. The act established the National Highway Traffic Safety Administration, and marked a historic shift in responsibility for automobile safety (which shifted from the consumer to the manufacturer). The legislation mandated a series of safety features for automobiles, beginning with safety belts and stronger windshields.^[26][27][28]

A 1972 National Highway Traffic Safety Administration safety commission report conducted by Texas A&M University concluded that the 1960-1963 Corvair possessed no greater potential for loss of control than its contemporaries in extreme situations.^[29] A different account, however, was given in John DeLorean's "General Motors autobiography", On a Clear Day You Can See General Motors, 1979 (published under the name of his would-be ghostwriter, J. Patrick Wright), in which DeLorean asserts that Nader's criticisms were valid. The specific Corvair design flaws were corrected in the second half (1965-1969) of the Corvair's production, although by then the Corvair name was irredeemably compromised.