Emissions standards for motorcycles took effect in 2006 under rules adopted by the Environmental Protection Agency. There were no previous emissions controls for motorcycles at all, but even under the new laws, "dirt" bikes for off-road use will be exempt, and manufacturers producing fewer than 3,000 vehicles a year were allowed an extra two years to comply.
The new standards add about $75 to the average cost of a motorcycle according to the EPA, but $250 according to the Motorcycle Industry Council. Why do you think motorcycle makers have not adopted voluntary emissions standards? Should they have done so? Why or why not?