Myths

MYTH…Starting an engine causes more pollution than idling.

TRUTH…No. Turning off an engine and restarting it after a minute or longer causes less pollution than keeping the engine idling and uses less fuel.


MYTH…It is better to idle the vehicle as turning the engine off and on wears it out.

TRUTH…No. Ignitions in modern cars have eliminated this problem. Idling dirties your engine with incomplete combustion increasing wear and tear. Excessive idling lets water condense in the vehicle’s exhaust system, which can lead to corrosion. It also causes spark plugs to become dirtier more quickly. This can cause an increase in fuel consumption by 4-5%.


MYTH…When it’s cold I need to keep my vehicle and passengers warm or warm up my engine.

TRUTH…It can take up to an hour for an engine to cool down. Turning off your engine, but keeping the ignition on and the fan blowing, will provide warm air for some time.


MYTH…Catalytic converters need to be hot to work properly.

TRUTH…Yes, but an idling engine does not keep a catalytic converter warm. They retain their heat for about 25 minutes after an engine is switched off.


MYTH…It doesn’t make any difference if I run my engine a few minutes longer.

TRUTH…If all drivers in central London switched off their engines, rather than idling unnecessarily, for 1 minute each day this could reduce emissions of fine particulate matter by 90kg per year!