Why You Shouldn’t Heat Up Your Car In Cold Winter Weather
Posted December 3, 2020 10:45 a.m. EST
Updated December 3, 2020 10:48 a.m. EST
If you live in a cold, snowy climate, you may be accustomed to firing up your engine in the winter and letting it run for a bit before you drive — something that’s made all the easier with remote-start technology.
While this age-old practice makes for a warmer, cozier car on frigid winter mornings, it poses problems, namely for your car’s engine and the environment. Plus, if your car was made in the last 25 years or so, it doesn’t need to warm up before you drive it, experts say.
In fact, the Environmental Protection Agency warns against the practice.
“Unnecessary idling of cars, trucks, and school buses pollutes the air, wastes fuel, and causes excess engine wear,” the EPA writes in their pollution-reduction guide. “Modern vehicles do not require ‘warming up’ in the winter, so there is no need to turn on the engine until you are ready to drive.”
Here’s what you need to know about warming up your car, including why it can be bad for your car’s engine and the environment, where idling might lead to a fine, and how the belief that you need to warm your car came about in the first place.
Why Idling Is Bad For Your Car And The Environment
Letting your car idle could decrease the life of your engine as it strips oil away from the engine’s cylinders and pistons, according to Popular Mechanics. Idling does little to warm your engine — but driving your car is the quickest way to warm up your engine.
Already, cold weather driving can reduce your vehicle’s fuel efficiency. Fuel economy tests show that, in city driving, a conventional gasoline car’s gas mileage is roughly 15% lower at 20 degrees Fahrenheit than it would be at 77 degrees Fahrenheit. It can drop as much as 24% for short trips in the 3-to-4-mile range, according to fueleconomy.gov. The amount of extra gas you waste by idling your car can vary, but compact cars with 2-liter engines consume about 0.16 gallons per hour.
Beyond wasting gas, idling increases the amount of vehicle exhaust in the air, according to an idling fact sheet from the South Carolina Department of Health and Environmental Control. Exhaust contains many pollutants that are linked to health problems, including asthma, other lung diseases and allergies.
Why Do People Think They Need To Warm Up Their Cars Before Driving?
The rationale that you should warm your car before you drive originates from a kernel of truth.
Cars made prior to the late 1980s required being warmed up for several minutes so that the correct blend of air and fuel could be delivered to the engine. Without the correct ratio, cars could sputter and stall, says Carfax. But by the mid-1990s, car manufacturers transitioned to electronic fuel injection, and sensors helped ensure the proper air-fuel mix, making it no longer necessary to let your car warm up.
Still, old habits die hard — and are passed onto the next generation of drivers who may have seen mom or dad letting their cars idle. To help remedy this, several states and municipalities have anti-idling laws that come with hefty fines if you leave your car running for too long.
The takeaway here? The best thing to do on those cold, snowy days is to start your car and take a minute to knock any ice off your windows, Popular Mechanics says, and make sure your defroster is working if it’s below freezing.