How to use: Estimate the cost of a trip. Enter the Distance in miles, your car's fuel economy (miles per UK gallon, or litres per 100 km if you prefer; check your car's handbook or trip computer), and the Fuel Price in pence per litre as shown at the pump or on your receipt. Results show the litres needed, the total cost in pounds, and the cost per mile and per kilometre. Example: 300 miles at 40 mpg (UK gallons) uses about 34.1 litres; at 145p per litre (an example price only) that is about £49.44, or £0.165 a mile. Use it for trip budgeting, comparing vehicles and tracking commuting costs. Petrol and diesel prices change, so use today's price.