Does my car need to warm up before driving it when it’s cold outside?

Anybody have childhood memories of your parents going out to start the car in the driveway on cold mornings? Many of us are in the habit today of running outside a 10 to 15 minutes before we need to leave for the day to get the engine warming and the heater blowing!

But, is it actually necessary?

According to the U.S. Department of Energy, most modern cars will warm up much faster just by driving. Unless your car’s windshield is frosted or iced over, there’s no reason to let your car idle for longer than about 30 seconds.

Idling is expensive, contributes to pollution and lowers your car’s fuel economy. On a cold day, your best bet is to begin driving after 30 seconds or so and to drive the car gently until it warms up. This reduces emissions and allows the engine to do its job – warming itself and your cabin.

In some states, idling your car is actually illegal! California, New York, Vermont and other states have laws on the books that may subject drivers to fines for unnecessary idling. In Texas, the transportation code prohibits leaving a vehicle unattended with the engine running and the key in the ignition.

Decades ago, idling to warm a car’s engine was necessary because of lower oil and gas quality. Today, however, the engine oil and fuel work in tandem to lubricate and power the engine. Popular Mechanics reports that when the engine is cold, more fuel is pumped into the combustion chamber to create warmth that powers the car. Engines run this way until they warm up, but idling contributes little to this process. Gasoline, a solvent, can actually clean away necessary lubricating oil from the engine’s combustion chamber, which over time reduces the life of certain parts.

Your best bet on cold mornings? Start the car, knock the ice of the windshield and drive gently for the first 10 to 15 minutes of your morning commute. And maybe throw a blanket in the backseat for the kiddos so they’re not chilled during the drive to school!

Sources:

US Dept of Energy:

https://afdc.energy.gov/files/u/publication/idling_personal_vehicles.pdf

Popular Mechanics: https://www.popularmechanics.com/cars/a19086/warming-up-your-car-in-the-cold-just-harms-engine/