How Cold Temperatures can affect your cars fuel consumption

As the shorts, vests and flip-flops are stored away and exchanged for thick coats, woolly hats and scarves, the winter months bring a host of new issues for car owners to look out for (aside from fashion!).

Not only does winter create problems for drivers such as slippery roads, icy windshields and reduced visibility from the snow or fog, one extremely overlooked issue during these months is that it also leaves drivers with a reduced petrol mileage consequently resulting in more of your hard earned cash going down the (fuel) drain. 

Cold temperatures can affect your cars fuel consumption

So how much does the cold weather reduce your fuel economy by?

According to the United States Environmental Protection Agency (EPA), ‘Fuel economy tests show that, in short-trip city driving, a conventional gasoline car’s gas mileage is about 12% lower at 20°F than it would be at 77°F. It can drop as much as 22% for very short trips (3 to 4 miles).’ (https://www.fueleconomy.gov/feg/coldweather.shtml)

What are the reasons for this and their solutions?

Problem 1: Frost

Almost every morning (and potentially evenings) you are going to have defrost and demist the windscreen to be able to see out of safely. This puts additional burdens on the engine and gives a fuel economy of 0 miles per gallon.

Solution: The easiest way to do this is to keep your car in a garage which will 1) reduce or eliminate the frost/mist and 2) increase the initial temperature of your engine. Should you not have access to a garage, the next easiest way is to purchase an anti-frost windscreen cover which can be brought for around £10.


Problem 2: Longer time to reach its optimum operating temperature

According to Rick Popely, a cars optimum operating temperature is between 195-220 degrees Farenheight (90.5-99 degrees Celsius) – https://www.cars.com/articles/should-i-worry-about-how-hot-my-engine-is-running-1420680334271/). 

Solution: Through combing trips you can avoid making your engine heat up multiple times a day – this will mean that your engine will not cool completely between stops and therefore it will require less fuel to heat it back up. This can easily done by undertaking tasks on the way to or from work or when picking the kids up from school. Also, similar to the first problem, keeping the car in a garage will help reduce the initial starting temperature.

Problem 3: Road conditions

With the threat of ice on the roads and water on the roads, you will often have to drive at safer and slower speeds. When driving at speeds below 30-40mph, instead of the best fuel economy of 55-65mph, this will drastically increase fuel consumption.

Solution: Whilst we strongly advise you not to drive at the most fuel economic speed for your own safety, we recommend that you drive at a constant speed and when required to slow down you try to keep moving as opposed to coming to a complete stop. This is easily done by looking ahead and anticipating what is going to happen.  

Problem 4: Tyre pressure decreases

As the temperature drops, the molecules inside the tyre slow down thus taking up less space within the tyre – this means that the molecules exert less force on the tire walls as there they take up less space and this leads to a decrease in tyre pressure. The reason that this will reduce fuel economy is this will increase the rolling resistance of the tyre on the road.

Solution: We recommend checking your tyre pressure regularly, ideally once a week. Your manual will often display the ideal tyre pressure, however this is for summer driving. The common rule thumb is to increase the pressure by between 0.1-0.2 bars from the recommended pressure.

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