It's a familiar routine on a cold morning: start the car, turn up the heat and let the engine idle in the driveway while you wait for it to “warm up.”

For generations, drivers have been told that driving a vehicle before the engine reaches operating temperature can cause unnecessary wear. But with modern vehicles, the advice has changed considerably.

So, is it actually bad to drive your car when the engine is cold?

The short answer is no — as long as you take it easy.

In fact, for most modern gasoline-powered vehicles, gently driving soon after starting the engine is generally a better way to warm it up than allowing it to idle for an extended period.

Why a Cold Engine Is Different

When an engine has been sitting for several hours, particularly in cold weather, its oil is cooler and thicker than it is at normal operating temperature. Once the engine starts, the oil pump begins circulating that oil through the engine to lubricate its moving components.

Modern motor oils are designed to flow at relatively low temperatures, but it still takes some time for the engine, oil, transmission and other components to reach their ideal operating temperatures. 

That means the first few minutes after starting aren't the time to see how quickly your car can accelerate onto the highway.

Starting the vehicle and driving normally is fine. Hard acceleration, high engine speeds, and heavy loads are better avoided until the vehicle has had some time to warm up.

You Probably Don't Need a 10-Minute Warm-Up

The idea of warming a car in the driveway for 10, 15 or even 20 minutes has its roots largely in older automotive technology.

Vehicles equipped with carburetors often needed additional warm-up time to run smoothly in cold conditions. Modern vehicles use electronic fuel injection and sophisticated engine-management computers that automatically adjust the fuel mixture based on temperature and other conditions.

As a result, most modern cars don't need an extended warm-up before driving.

On a cold morning, you can generally start the vehicle, give it a brief moment for the engine to settle and oil to begin circulating, then drive away gently.

There is an important exception: safety.

If the windshield is covered in ice, snow or heavy condensation, take whatever time is necessary to completely clear it before driving. Being able to see clearly is considerably more important than saving a few minutes of idling.

Gentle Driving Warms More Than the Engine

Driving has another advantage over sitting in the driveway: your engine isn't the only part of the vehicle that needs to warm up.

The transmission, wheel bearings, tires, differential and other components also experience colder temperatures. Letting the engine idle may warm the engine somewhat, but it does little to warm many of those other components.

Driving gently allows the entire vehicle to gradually reach operating temperature.

That's why the first several miles of a cold-weather trip are best treated as a warm-up period for the whole car rather than just the engine.

Avoid flooring the accelerator, racing the engine or immediately asking the vehicle to perform at its maximum capability.

What About the Temperature Gauge?

Many drivers wait until the dashboard's coolant-temperature gauge reaches its normal position before assuming the engine is fully warmed.

But coolant temperature doesn't tell the entire story.

Engine oil can take longer to reach full operating temperature than coolant. So even if the temperature gauge looks normal, the oil and other drivetrain components may still be warming.

You don't need to drive timidly for half an hour, but giving the vehicle some reasonable time before demanding maximum performance is a good habit.

This is particularly relevant for turbocharged or high-performance engines, where drivers may be tempted to use higher engine speeds and heavier throttle.

Does Idling Hurt the Car?

A few minutes of idling isn't likely to destroy a modern engine. Sometimes it's unavoidable, particularly while defrosting windows.

But extended idling generally isn't accomplishing as much as many drivers think.

The engine warms more slowly while idling than it does under a light driving load. You're also burning fuel while traveling exactly zero miles.

For most everyday driving, there's little reason to start the vehicle and leave it running for 15 minutes simply because it's cold outside.

Extremely Cold Weather Is Different

There is obviously a difference between a chilly 40-degree morning and starting a vehicle when temperatures are well below zero.

In extreme cold, oil becomes thicker, batteries produce less power, and virtually every mechanical component in the vehicle is dealing with harsher conditions.

Giving the engine a little additional time before driving can be reasonable under those circumstances. Even then, extended idling generally isn't necessary unless recommended by the vehicle manufacturer or needed to safely clear the windows.

Drivers living in extremely cold climates may also benefit from equipment such as engine-block heaters.

What About Diesel Engines?

Diesel vehicles deserve their own consideration.

Modern diesels have also changed dramatically, but some diesel engines use glow plugs or other systems to assist with cold starting. Drivers should follow the starting procedure outlined in the owner's manual, including waiting for the appropriate dashboard indicator when necessary.

As with gasoline engines, gentle driving while the vehicle warms is usually preferable to immediately placing the engine under a heavy load.

The Bottom Line

Driving a cold engine isn't inherently bad for your car.

Driving a cold engine hard can be.

For most modern vehicles, the best routine is simple: start the engine, allow a brief period for everything to stabilize, make sure the windows are clear and then begin driving.

For the first several minutes, accelerate smoothly, keep engine speeds reasonable and avoid heavy loads. As the engine and drivetrain reach operating temperature, you can drive normally.

Your grandfather may have needed to let his carbureted car warm up in the driveway before heading to work.

Your modern vehicle probably doesn't.

Sometimes the best way to warm up your car is simply to drive it.