Check your car's manual, the manufacturer's website, or the official DVLA fuel consumption figures. Real-world MPG is typically 15–20% lower than official figures. You can also calculate it manually: fill up, note the mileage, drive normally, fill up again, divide miles driven by litres used × 4.546.
What is the average UK fuel price?
Petrol and diesel prices change daily. Check gov.uk fuel prices for the current weekly average.
How do I convert MPG to L/100km?
L/100km = 282.481 ÷ MPG. So 40MPG = 7.06 L/100km. Our calculator handles both automatically.