Clean Air Week 2023

Idling FAQs  

Myth rather than fact is driving the prevalence of idling in the public realm.

For example:    

My engine needs to stay on to keep the battery warm: False.    

Improved battery design has largely eliminated this threat. Contrary to popular belief, excessive idling is not an effective way to warm up your vehicle, even in cold weather. The best way to warm it up is to drive it. In fact, with today’s computer-controlled engines, even on cold winter days no more than two to three minutes of idling is usually enough warm-up time before starting to drive. Please consult your owner’s manual or your vehicle service advisor if you would like a recommendation specific to your vehicle or climatic conditions.   

With modern vehicle technology and more fuel efficient cars, why do I have to worry about idling?    

Vehicles emit 99% less than vehicles built in the 1970s but one component in tailpipe emissions is directly impacted by the type and amount of fuel your vehicle uses – carbon dioxide (CO2). This is the principal greenhouse gas linked to Climate Change. Every litre of petrol that is burned produces about 2.3kg of CO2. The more fuel you use, the more CO2 you produce.   

Turning the engine on and off wears it out: False.    

It creates less wear and tear than idling. Electronic ignitions in modern cars have eliminated this problem.   

Catalytic converters need to be hot to work properly: True   

An idling engine does not keep a catalytic converter warm. They retain their heat for about 25 minutes after an engine is switched off anyway.   

When it’s cold I need to keep my engine running to keep my car and passengers warm :   False.

It can take up to an hour for the engine to cool down. Turn your engine off but keep the ignition on and the fan blowing and the car will stay warm for some time.   

Idling keeps an engine in better condition: False    

Idling means incomplete combustion, leading to a build-up of residue in an engine, increasing wear and tear.   

Starting an engine uses more petrol than idling.: False    

In fact, for a majority, engines idling for more than 10 seconds use more petrol that starting the motor.   

The best way to warm up your vehicle is to leave the engine running for a few minutes: False   

You only need to run the engine long enough to get the oil circulating (about 30 seconds) before driving away.   

Idling reduces wear and tear on your engine particularly when cold: False.   

Idling creates wear and tear on your engine because fuel does not combust completely, and some fuel residue can condense on cylinder walls. Excessive idling can cause condensation to form in the exhaust, which may result in corrosion and reduced lifespan of the exhaust system. But the most severe damage is to the connecting rod bearings. This happens because of the relatively slow speed of the engine, more pressure is exerted on the bottom centre and top centre of the bearings.   

How can burning one litre of petrol (that weighs 0.75KG) produce 2.3kg of CO2?    

Most fuels are hydrocarbon-based mixtures rich in both hydrogen and carbon. When burned they undergo a chemical reaction resulting in the release of energy (primarily heat) and combustion by-products. When fuel is burned to operate a vehicle, a carbon atom combines with two oxygen atoms from the air to produce a corresponding number of CO2 molecules (the other primary by-product of combustion being H2O – water). Petrol is rich in carbon; in fact in a litre of petrol that weighs about 0.75 kg, about 86% of the weight is made up of carbon. That is a lot of CO2 molecules – and is how approximately 2.3 kg of CO2 are produced for each litre of fuel that is burned! If you’re a motorist who drives 20,000 km each year‚ you’re emitting more than four tonnes of CO2 per year that’s about three times the weight of your car!   

What do countries around the world recommend as idling turn-off times for their engines?    

In Europe, the recommended guidelines for turning engines off are 10 seconds in Italy and France, 20 seconds in Austria, 40 seconds in Germany and 60 seconds in the Netherlands. In the United States the Environmental Protection Agency’s Smartway and DriveWise programs recommend turning the engine off if you’re stopped for more than 30 seconds.   

It is more economical and fuel-efficient to leave my car running for a few minutes than to constantly turn it off and on: False. 

Stop/start systems were introduced in order to reduce emissions and fuel consumption.