How Fuel Costs Are Calculated
The fuel cost formula converts your car’s efficiency from miles per gallon into litres consumed, then multiplies by the price per litre. First, divide the journey distance by your MPG figure to get the number of imperial gallons needed. Multiply this by 4.546 to convert to litres, since UK fuel is sold in litres. Finally, multiply the litres by the price per litre to get the total cost in pounds.
Real-world fuel economy is typically 10 to 20 per cent worse than the official manufacturer figures, especially in urban driving conditions. Factors such as driving style, tyre pressure, vehicle load, air conditioning use and traffic conditions all affect actual consumption. For the most accurate estimate, use a figure based on your own driving experience rather than the brochure number.
Petrol vs Diesel Running Costs
Diesel cars typically achieve 15 to 25 per cent better fuel economy than equivalent petrol models, which can offset the higher price of diesel fuel for high-mileage drivers. However, diesel vehicles often cost more to buy, insure and maintain, with diesel particulate filter issues adding potential repair costs for cars used mainly for short journeys. For drivers covering fewer than 10,000 miles per year, petrol is usually the more economical choice overall.
Supermarket fuel stations consistently offer some of the cheapest prices in the UK, often 3 to 5 pence per litre below motorway service stations. Using fuel comparison apps and filling up at the cheapest local station can save well over 100 pounds per year for a typical driver. Loyalty schemes and supermarket fuel vouchers can provide additional savings.
Reducing Your Fuel Bills
Simple changes to your driving habits can reduce fuel consumption by 10 to 15 per cent. Accelerate gently, maintain a steady speed, anticipate traffic flow to avoid harsh braking, and use the highest appropriate gear. Check tyre pressures monthly, as underinflated tyres increase rolling resistance and fuel consumption. Remove unnecessary weight from the boot and take off roof bars or boxes when not in use, as these create aerodynamic drag at higher speeds.
Compare your running costs against an electric vehicle using our EV vs petrol calculator, or check your actual fuel economy with the miles per gallon calculator. For vehicle tax rates and motoring regulations, see GOV.UK.
This calculator provides estimates for guidance only. Results are based on the figures you enter and typical UK averages. This is not professional, financial, medical or legal advice. Always consult a qualified professional for specific guidance.