Drivers face increased fuel consumption and potential inaccuracies in fuel gauges due to an impending heatwave, prompting urgent advice to refuel before Tuesday.
As summer temperatures are forecast to climb significantly this weekend, motorists are being advised to fill their petrol and diesel tanks before Tuesday, June 23. The Met Office has issued an amber alert for extreme heat, with temperatures expected to reach a sweltering 34C in London and exceed 30C across most of England and Wales. This period of intense heat, beginning Monday and lasting until Tuesday evening, presents an often-overlooked challenge for drivers: increased fuel usage.
Heat’s Impact on Fuel Economy
Warmer weather can lead to a quicker depletion of fuel for several reasons. Analysis from the US Department of Energy indicates that drivers may adopt habits that consume more fuel, such as increased use of air conditioning and opening windows for ventilation. While hot weather can theoretically improve engine efficiency by allowing engines to reach optimal temperatures faster and reducing aerodynamic drag, the comfort measures taken by drivers can significantly negate these benefits.
Specifically, the use of a vehicle’s air conditioning system is identified as a primary contributor to reduced fuel economy in hot conditions. The extent of this impact can vary depending on external factors like ambient temperature, humidity, and solar intensity. Under extreme heat, air conditioning use can decrease a conventional vehicle’s fuel economy by over 25%, particularly on shorter journeys. For hybrid, plug-in hybrid, and electric vehicles, the percentage reduction in efficiency can be even greater.
Rising Fuel Prices and Strategic Refueling
In the current economic climate, where fuel prices remain elevated following recent global events, drivers are keen to maximize every drop of fuel. With petrol averaging 154.72p per litre and diesel at 174.30p, according to recent data from the RAC, any unnecessary expenditure is to be avoided.
Avoiding Stranding in Traffic
Beyond the direct impact on fuel consumption, experts also highlight the risk of becoming stranded in traffic during a heatwave. Driving with a low fuel level is ill-advised at any time, but the accelerated fuel depletion in hot weather means drivers cannot rely on their usual estimations of remaining range. To prevent being stuck in a traffic jam on a hot day, it is recommended to refuel proactively.
Debunking a Fuel Tank Myth
Concerns have previously circulated about the safety of filling fuel tanks during hot weather, with some suggesting a risk of vehicle ‘explosion.’ However, this is a widely debunked myth. All fuel systems in passenger vehicles are engineered to safely manage the expansion of fuel and vapors. There is no inherent risk of explosion from filling a fuel tank, and drivers should feel no apprehension in doing so.
Optimal Fuel Economy Conditions
While extreme heat reduces efficiency, experts note that there is an optimal temperature range for fuel economy. Temperatures around 20C are generally more efficient than very cold conditions. Fuel efficiency can drop by approximately 10% at -5C compared to 20C, with short trips under four miles experiencing penalties of 20% or more. The ideal ‘sweet spot’ for fuel economy is considered to be between 15C and 20C. However, as temperatures rise beyond 32C, engine efficiency begins to decline, and the risk of overheating increases.
