When a vehicle is emitting excess levels of smoke, chances are that it is not properly tuned or maintained. When a vehicle is poorly tuned or maintained, the equipment on the vehicle designed to control the level of pollutant emissions also may not function properly.
Smoke from petrol engine vehicles (most cars) is mainly due to excessive wear.
Diesel vehicles (most trucks) may emit smoke from poor injector maintenance, excessive fuel delivery rates or poor driving technique (for example, lugging which is labouring the engine in too high a gear).
Smoke emissions mean that the vehicle is wasting fuel and engine damage is probably occurring. Routine servicing will eliminate many problems that cause smoke emissions and save you time and money.