Do Exhaust Controls Really Work? — Second Report 670689
Emission tests on 739 cars (1966 and 1967 models) equipped with exhaust controls in public use confirm that the vehicle manufacturers have done a good job of designing cars with low emissions. However, field data on emissions higher than proving ground results, and deterioration of emissions with mileage, indicate that much more effort is needed with regard to proper engine adjustments and quality control on the production line as well as better servicing of the engines in the field. Continued effective emission control after initial sale of the new car is the responsibility of the states.