What is required in addition to a muffler on vehicles manufactured after 1968?

The requirement for an exhaust emission system in addition to a muffler on vehicles manufactured after 1968 is rooted in environmental regulations aimed at reducing air pollution. The catalytic converter, which is part of the exhaust emission system, plays a crucial role in processing exhaust gases before they are released into the atmosphere. This system works to minimize harmful emissions by converting toxic pollutants into less harmful substances, thus contributing to cleaner air.

Vehicles manufactured after 1968 were built during a time when emissions control became increasingly important, leading to the implementation of stricter regulations. Therefore, having both a muffler, which reduces noise levels, and an exhaust emission system, which controls exhaust emissions, is essential for compliance with emissions standards and for promoting public health.

A sound system, while it may enhance the driving experience, does not relate to vehicle emissions or noise regulations. An automatic gear system is a feature related to vehicle operation rather than emissions control and does not contribute to the requirements tied to environmental regulations.