Motorists are being advised to top up their tanks before Monday where possible, as scorching conditions are set to return across several parts of the UK, potentially causing vehicles to burn through fuel at a faster rate than usual. The Met Office has predicted a return to warm weather beginning on Sunday and reaching its peak on Monday in London and various other regions across the UK, particularly across the south of England. Temperatures could reach 30°C on Sunday, climbing to 32°C on Monday, according to forecasters, before settling at around 30°C for the majority of the following week.
Regional Temperature Breakdown
Liverpool is set for a warm and increasingly sunny week, with temperatures climbing steadily after a cloudy start. Monday and Tuesday will be mostly cloudy and breezy, with highs of around 21°C to 22°C. Conditions are expected to improve from Wednesday, when sunny spells develop and temperatures reach 24°C. The warmest weather is forecast for Thursday and Friday, with plenty of sunshine and highs of 27°C to 28°C. Warm conditions are expected to continue into next weekend, with temperatures remaining in the high 20s.
Many motorists may be unaware that warmer temperatures present an unexpected hazard relating to their fuel tank, which could leave them short. In hot conditions, petrol or diesel actually depletes more rapidly than usual due to driver behaviour, and in extreme heat it can even have a negative impact on fuel economy.
Fuel Prices Remain High
Fuel costs have risen sharply in recent months as a result of the conflict in Iran, and despite a modest easing at the pumps, prices remain considerably high compared to previous levels. At present, petrol stands at an average of 154.72p per litre, while diesel sits at 174.30p according to the RAC, meaning drivers will be keen to avoid any unnecessary wastage.
Why Hot Weather Reduces Fuel Economy
Vehicles consume more fuel in hot weather, both directly and due to how motorists drive. Consequently, your fuel gauge might become unreliable and fail to provide an accurate reading of how much petrol or diesel remains in your tank, reports the Express. Research from the US government indicates that drivers are more likely to adopt behaviours that deplete fuel faster when temperatures rise, including opening windows and running air conditioning.
The US Department of Energy says: "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. However, keeping comfortable in hot weather by rolling down the windows or using the air conditioning (A/C) can reduce fuel economy. Running the vehicle's air conditioning is the main contributor to reduced fuel economy in hot weather. Its effect depends on a number of factors, such as the outside temperature, humidity, and intensity of the sun. Under very hot conditions, A/C use can reduce a conventional vehicle's fuel economy by more than 25%, particularly on short trips. The A/C's effect on hybrids, plug-in hybrids, and electric vehicles (EVs) can be even larger on a percentage basis."
Avoid Getting Stuck in Traffic
Another compelling reason to fill your tank before warmer conditions arrive is to avoid becoming stuck in traffic during sweltering weather. Specialists at PassMeFast.co.uk say: "When it comes to topping up the petrol in your car, there are two kinds of people: those who refill as soon as the fuel tank gets to around a quarter full, and those who are happy to drive around with the fuel warning light on. The thing is, when the weather's nice and warm, your car's fuel levels drop a lot quicker than usual. This means you can't rely on your normal estimations of how much time you have left before needing to fill up. To avoid getting stuck in the middle of nowhere, or at the centre of a traffic jam on a hot day (both nightmare scenarios), make sure you head to the petrol station in good time. Playing it close to the line is just not worth it if the sun's out!"
Myth of Explosion Debunked
Motorists have also previously been warned against filling up their vehicle during warm conditions because of concerns the car could "explode" in the sunshine. Fortunately, this isn't a genuine issue and is, in reality, a myth. RAC spokesperson Rod Dennis said: "There is no truth in this. All fuel systems on passenger vehicles are designed to cope with any expansion of fuel, or vapour coming from the fuel. There is no risk of explosion from filling up a fuel tank fully and drivers should have no concerns in doing so."
Optimal Temperature for Fuel Efficiency
That said, when it comes to operating a car as economically as you can, there's an ideal balance between cold conditions and warm conditions where efficiency is at its best, according to specialists. Temperatures around 20°C will deliver superior fuel efficiency compared to very cold conditions, though as temperatures climb higher, those benefits begin to diminish once more. Fuel Finder UK says: "According to official fuel economy tests, your car's efficiency drops by around 10% at -5°C compared to 20°C. For short trips under four miles, that penalty can reach 20% or more." According to Fuel Finder, the optimal range for fuel economy sits between 15°C and 20°C, but once temperatures reach 32°C, engine performance decreases and the possibility of overheating becomes a concern.
