Cold Weather Q & A

 Reduce Vehicle Idling: Cold Weather and Idling: Q & A

Fuel-efficient driving becomes particularly challenging in winter months because fuel consumption and pollution output are much higher in cold weather. There are many misconceptions about idling to warm up your vehicle. The following points are provided by Natural Resources Canada Office of Energy Efficiency's (OEE) AutoSmart Guide and website


Q: Is it important to idle my vehicle for a few minutes to warm up the engine in winter?
A: No. Tests show that you need no more than 30 seconds of idling to circulate the engine oil before you drive away on cold days. Anything longer just wastes money and produces needless greenhouse gas emissions. Remember, more than the engine needs to be warmed - so do the tires, transmission, wheel bearings and other moving parts. As well, the catalytic converter doesn't function at its peak until it reaches between 400°C and 800°C. The best way to warm the engine and all other components is to drive your vehicle. Also, using a block heater will allow the engine to start more easily and reach its peak operating temperature faster. In temperatures of -20 degrees Celsius, block heaters can improve overall fuel economy by as much as 10 percent or more.

Q: In terms of frosted windows and visibility concerns, isn't it unsafe to drive my vehicle shortly after a cold start?
A: Never drive your vehicle before the windows are defrosted. You can speed up the process and prevent your car windows from fogging up by opening a window as soon as you enter the vehicle. Also, clear snow from the air intake on top of the hood otherwise the defroster will draw moisture into the system and fog up the windshield.

Q: Isn't it damaging to my vehicle to drive it when it's still very cold?
A: Although it is important to drive away as soon as possible after a cold start, it is true that you should avoid high speeds and rapid acceleration for the first five kilometres or so. The goal is to bring the whole vehicle up to peak operating temperature as quickly as possible while maximizing fuel economy. In fact, a study conducted by the OEE concluded that restarting a vehicle numerous times (as opposed to leaving it idling) has a relatively small impact on engine components such as the battery and starter motor. The study estimates that component wear caused by restarting the engine adds another $10 per year to the cost of driving, which will likely be recovered several times over in fuel-cost savings.

Q: Climbing into a cold car during winter is very uncomfortable. How do I avoid this?
A: Use a block heater to warm the vehicle and engine before you start it. This also reduces engine wear, improves fuel efficiency and reduces emissions by up to 20 percent in cold conditions. Use an automatic timer or plug in your block heater two hours before you plan to start the vehicle. Avoid using a remote car starter. It encourages you to start your car before you're ready to drive it, resulting in unnecessary idling. Lastly, remember to dress for the weather.

Q: When it's cold, isn't it more economical and fuel-efficient to leave my car running for a few minutes than to constantly turn it off and on?
A: No. If you're going to be stopped for more than 10 seconds (except in traffic), you'll save fuel and money by turning off the vehicle and then restarting it when you're ready to drive again. Every 10 minutes of idling costs you at least one-tenth of a litre in wasted fuel - and up to four-tenths of a litre if your vehicle has an eight-cylinder engine. As well, restarting a car many times doesn't wear out the battery and starter motor too soon. And catalytic converters stay warm for up to 25 minutes after you turn off the engine, so frequent stops and starts don't produce the large amount of harmful emissions seen with cold starts.

Q: What else can I do to reduce fuel consumption in the winter?
A: Get rid of the snow build-up in wheel wells and under the bumper to decrease weight and rolling resistance, which in turn reduces fuel consumption. Under-deflated tires also contribute to unnecessary increases in fuel consumption, which can be avoided by checking tire pressure regularly, especially after drops in temperature. Also, effective trip planning is important in winter to avoid making more cold starts than needed. For example, combine small errand trips into one large trip allows the engine to remain relatively warm. Lastly, simply "take it easy" - make fewer slips, slides and spins, which wastes fuel.

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