How winter weather affects your fuel economy

As temperatures plummet during winter, the consequences on car fuel efficiency come sharply into focus, particularly for conventional gasoline vehicles. Around 20°F, drivers may witness a substantial 24% drop in gas mileage, a phenomenon exacerbated during city driving and short trips, where a 15% lower efficiency becomes evident.

 This impact isn’t uniform across all vehicle types, as hybrids may suffer a 30% to 34% fuel economy drop, while electric vehicles experience a staggering 39% . Decrease in mixed city and highway driving. Personal experience with various vehicle models underscores the reality of a 10% to 20%. Fuel economy loss during city driving and a 15% to 33% loss on short trips in cold conditions.

Delving into the mechanics reveals that cabin heating contributes significantly to the extra energy consumed in cold weather, resulting in an 8% lower fuel economy at 20°F compared to a milder 75°F. This translates into a 41% decrease in driving range, highlighting the intricate relationship between temperature and fuel efficiency. 

Understanding these nuances becomes paramount for drivers seeking to optimize their vehicles’ performance during winter journeys. Navigating the challenges posed by cold temperatures and ensuring a smoother, more efficient driving experience.

Cold Air Density:

Cold temperatures have a profound impact on the efficiency of your car’s fuel consumption. One often-overlooked aspect is the effect of cold air on the density of the atmosphere. Unlike warm air, cold air is denser, causing increased aerodynamic resistance as your vehicle moves through it. This heightened resistance translates to a significant power and fuel compensation loss, especially during the winter months.

In regions like Victoria, where average winter wind speeds compound the issue, the difference in fuel efficiency can range from 15 to 20 percent. This phenomenon becomes even more pronounced for cars equipped with roof racks or a roof box. As these additions increase aerodynamic drag, resulting in a notable fuel-economy hit. Personal experience has taught me that removing these accessories during the winter months can make a substantial difference in maintaining fuel efficiency.

Friction from Cold Oil:

Moving beyond the air itself, the impact of cold temperatures extends to the very lifeblood of your engine—its oil. Cold weather increases the friction within the oil, affecting its viscosity or thickness. Imagine cold oil in your car’s engine like honey in your pantry—it doesn’t flow as smoothly. This increased friction can lead to a fuel efficiency penalty, particularly during short trips where the engine doesn’t reach optimal operating temperatures.

To counteract this, using a specific winter-graded engine oil is crucial. During winter, I’ve found that consulting with a reliable mechanic and opting for a winter-grade lubricant earns a well-deserved thumbs-up for maintaining efficiency.

Battery Efficiency:

As the mercury drops, the efficiency of your car’s signs of a failing battery becomes a critical concern. The chemistry of batteries is such that they operate optimally within certain temperature ranges. For both petrol-powered and electric vehicles (EVs), the cold weather can affect battery performance. In traditional cars, the alternator has to work harder to charge the battery, leading to increased fuel use.

For EVs, the impact is even more pronounced. The regenerative-braking system, designed to boost efficiency, is less effective in colder temperatures. Drawing from personal experience, ensuring your EV is adequately charged and utilizing pre-heating while still on charge can mitigate these challenges during the winter months.

Power-Hungry Features:

In the pursuit of a warm and cozy cabin during winter. We often overlook the toll it takes on our vehicle’s fuel efficiency. The culprits? Power-hungry features like window defrosters, seat heaters, and steering-wheel heaters. These creature comforts draw power from the alternator, forcing it to work harder and impacting overall fuel economy.

Whether you drive a conventional car or an EV, the penalty for keeping these energy-sapping warming gizmos on can be substantial. According to the US EPA, running the heater on an EV in cold weather can make it significantly less economical. Balancing the need for warmth with strategic use of these features is key to maintaining fuel efficiency during winter.

Tyre Pressure Drop:

As temperatures plummet, another critical factor affecting your car’s efficiency is the drop in tyre pressures. Cold air makes the air inside your tires denser, causing a reduction in pressure. This not only results in increased rolling resistance but also forces the car to work harder to maintain momentum.

Regularly checking and ensuring your tyres are inflated to the specified pressure becomes crucial during winter. It’s a simple yet effective measure to counteract the impact of cold temperatures on your car’s fuel efficiency.

Slippery Roads and Increased Effort:

The challenges of winter driving go beyond temperature alone. Slippery roads due to wet or slick conditions make your car work harder. Reduced traction translates into more power being used to maintain momentum. This is particularly relevant for all-wheel-drive or four-wheel-drive vehicles, where increased drivetrain friction leads to higher fuel consumption.

Fundamental safe driving practices become even more beneficial during cold weather. Slowing down, maintaining a safe distance from the car ahead, and making smooth throttle, braking, and steering inputs can maximize the odds of staying safe on the road while preserving your car’s precious energy source.

Improving Fuel Economy in Cold Weather:

• Park in a warmer place, like a heated garage, to raise the initial temperature of both the engine and cabin, resulting in a noticeable reduction in fuel consumption during the first miles.

• Combine errands to minimize the amount of driving, reducing the impact of less fuel-efficient cold starts with a cold engine. Adopt habits like minimizing idling and driving off gently after 30 seconds of warm-up to make the engine warm up faster—a practice many manufacturers recommend for modern engines.

• Leverage features wisely to maintain comfort without sacrificing efficiency. Use seat warmers and defrosters to stay warm, reducing the need for high cabin temperatures. Check tire pressure regularly to ensure optimal fuel efficiency. Follow your vehicle manufacturer’s guidelines for the recommended type of oil for cold weather driving.

• For plug-in hybrids and electric vehicles, preheat the cabin while plugged into the charger to ensure a comfortable start and extend the vehicle’s range, optimizing energy use. These practices not only lead to decreasing fuel costs but also actively contribute to reducing emissions—a win-win for your wallet and the environment.

In my personal experience, incorporating these habits has not only saved money but also made winter drives more efficient and enjoyable. Every small adjustment adds up, making cold weather driving both eco-friendly and cost-effective.

Why is winter fuel economy lower?

As temperatures plummet, the intricate dance of mechanical components within your vehicle becomes more challenging. Cold temperatures thicken engine oil, increase friction in the engine, transmission, and drive-line fluids, creating a perfect storm for decreased fuel efficiency. 

Short trips exacerbate the issue, as engines struggle to reach their fuel-efficient temperature during brief journeys. The added load of heated seats, window defrosters, and heater fans further impacts fuel economy, turning every winter drive into a battle against inefficiency.

On the road, the challenges persist. Colder air results in denser conditions, amplifying aerodynamic drag at highway speeds. Winter-grade gasoline compounds the problem, offering less energy per gallon than its summer counterparts. In severe winter weather, the drop in miles per gallon becomes even more pronounced. Icy, snow-covered roads diminish tire grip, forcing the vehicle to work harder and wasting energy.

 Even with four-wheel drive, increased rolling resistance on slick roads leads to lower-than-normal fuel economy, underscoring the need for adapting driving habits to winter conditions. In this season, every component, from battery performance to the alternator, plays a crucial role in maintaining optimal fuel efficiency.

Conclusion

In conclusion, the impact of cold temperatures on car fuel efficiency is a multifaceted challenge that becomes pronounced during winter. As temperatures drop, the intricate dance of mechanical components within the vehicle, such as engine oil thickening and increased friction, creates a perfect storm for decreased fuel efficiency.

 Short trips and the use of power-hungry features further exacerbate the issue, making every winter drive a battle against inefficiency. On the road, denser air and winter-grade gasoline compound the challenges, resulting in a notable drop in miles per gallon, especially on icy, snow-covered roads. 

Adapting driving habits, optimizing vehicle components, and incorporating practical measures such as maintaining optimal tire pressure become crucial for navigating the complexities of cold weather and ensuring a smoother, more fuel-efficient driving experience. In my personal experience, adopting these practices not only saved money but also enhanced the overall efficiency and enjoyment of winter drives, showcasing the tangible benefits of understanding and addressing the nuances of winter fuel economy.

FAQs

What happens to petrol when it gets cold?

Because diesel and gasoline are fluids, they become much denser when it is cold. We purchase fuel on a volume metric so this affects the amount of fuel you purchase when it is cold vs when it is hot. We promise there is a science to this!

How does temperature affect fuel efficiency?

Hot weather can increase fuel economy – the engine warms up to an efficient temperature faster; summer grades of gasoline can have slightly more energy; and warm air causes less aerodynamic drag than cold air.

Is it better to get fuel when it’s cold?

Whilst temperature does have a very measurable effect on the volume of gas you get, filling up in a morning when the temperature is cold, as opposed to in the middle of a hot afternoon has no practical effect on the volume of gas you’re actually getting because, in all but extreme cases, the temperature the gas will be .

Does cold weather affect diesel fuel economy?

During the cold winter months, fueling stations will switch to winter blend fuels. Winter blend fuels contain additives to lower the temperature at which diesel fuel gels. These additives adversely affect the cetane level of the fuel and can result in a loss of one-half to three-quarters of an mpg in fuel efficiency.

Can petrol fuel freeze?

This depends on the type of gasoline and its components. Different elements of the fuel are made from unique molecules, which will become more solid at different times. You could probably give it a range of about -40 and -200 degrees Fahrenheit, with most of it freezing at -100 degrees.