| The method of providing traction to any of the wheels of a vehicle, as conditions require. Depending on the system, it may be full-time or part-time. | |
| Chlorofluorocarbon | |
| A system that provides fresh air to the exhaust system under controlled conditions to reduce emissions. The air source can be a pulse-air pump or an electrical or belt driven pump. Upstream air injection goes into the exhaust manifold to assist in after burning HC laden exhaust gases. Downstream air injection goes into the oxidation bed of the catalytic converter to help oxidize HC and CO emissions. | |
| Air-conditioning |