An automotive tune-up clinic for the purpose of reducing undesirable exhaust emissions was held March 14, 1970, as part of an environmental teach-in. The event was sponsored by the student branch of SAE at the University of Michigan. The results of this event clearly show that improper automotive maintenance can be a major factor in atmospheric pollution. It was found that idle hydrocarbon emissions were reduced by an average of 55% with a tune-up in which the idle mixture ratio and speed were adjusted for minimum carbon monoxide emissions. Our conclusion is that the individual motorist must begin to develop an attitude of responsibility toward the maintenance of his automobile to ensure low emissions.