Home > Maintenance > Do You Need to Warm Your Car Up?

Do You Need to Warm Your Car Up?

That howling wind outside portends that an especially cold day awaits you once you exit the comfort and security of your warm home. Your poor car has been sitting in your driveway or in your cold garage, and you believe that it may have trouble starting.
What you may consider doing is starting your car, running back inside to finish your piping hot cup of coffee and then returning to your vehicle to join the thousands of other motorists who are also making their way to work today.

Is warming your car first a wise idea? Is it even necessary? What impact on the environment will idling your car have? We’ll explore these (and other) matters, just as the latest cold snap refuses to let loose its icy grip.

Back in the Day

To quickly respond to the lead question, that answer is usually always no. Allowing cars to warm up on cold days is a tradition that goes back decades, to the days when vehicles had carburetors.

Then, warming up the car made sense as it could take several minutes for the right blend of air and fuel to be delivered to the engine. Without the correct blend, cars would sputter, stall and leave drivers stranded.

By the late 1980s and certainly no later than the early 1990s, all car manufacturers completed the transition to electronic fuel injection. Sensors working in conjunction with injectors ensured that the right air-fuel mix was always delivered promptly. Therefore, warming up cars equipped with fuel injection systems simply became unnecessary.

Should a new car still have trouble starting promptly, other factors such as a clogged injector, a frozen fuel line or a dead battery might be the culprit. But those are issues separate from the topic at hand.

Unfortunately, certain habits are difficult to break and misinformation is rampant. Chances are if you had one of those older models and later sold it, you passed this habit on to the next generation. It is time to lay the fallacy to rest, especially for any car built within the past 25 years.

Fuel Consumption and Pollution

Idling your car consumes fuel — you will consume anywhere from one-quarter to one-half a gallon of fuel for every hour your car idles according to the EPA. If you idle your vehicle daily for 10 minutes before leaving for work and do so for three months out of the year, then that’s 660 minutes or 11 hours of wasted gas (22 days per month x 3 months). Up to 5.5 gallons of gasoline is wasted and with it $20 you could have spent elsewhere.

Idling also contributes emissions that pollute the environment. And that’s one reason why policymakers have implemented various idling reduction programs to cover school buses and fleet vehicles. Likewise, your daily 10-minute warm-up also contributes a pound of carbon dioxide to the air, what can lead to climate change.

Besides wasting fuel and polluting the air, there is a third factor that should be considered when idling your car: engine wear. Excessive idling can take its toll on your engine, affecting the cylinders, spark plugs and the emissions system. Moreover, if you are idle for more than 10 seconds — such as, at a stop light or train tracks — it may make sense to turn off the ignition. You will use less gasoline restarting the car than when idling, which is why manufacturers have installed automatic stop/start technology on a number of vehicles.

Cold Day Operating Guidelines

So, how should you start your car on a cold day? Just as you do on any other day by starting your car and carefully exiting your driveway or parking spot and avoiding excessive engine revving.

Within seconds, your car is ready for normal driving, which means you can reach highway speeds immediately. Turn on your heater, seat warmer and the heated steering wheel after you start your car. And if your car has ice on it, scrape it off before starting your vehicle.

Finally, excessive idling will also do a number on a figure that may have you infatuated with your vehicle: its miles per gallon (mpg) average. Colder air alone makes it more challenging for your vehicle to attain those numbers, and excessive idling certainly does not help.

If you have questions about this story, please contact us at Editors@carfax.com