How to Compare Fuel Costs Before a UK Autumn Drive

Business & Money Desk 2026-10-28 10:47 4 min read

Vintage petrol station pumps under a roof in a quiet UK town setting.

Planning a longer autumn drive in the UK? Estimate how much fuel your actual route may use, check current prices at nearby forecourts, and compare the total journey cost before choosing where to refuel. A station with a lower price per litre may add enough distance to your trip to make the overall journey less economical.

Calculate how much fuel your route may use

Start with the distance you expect to drive and your vehicle’s fuel economy. Use the figure that best reflects your car and driving conditions: fuel use can vary with speed, traffic, weather, passengers, luggage and driving style.

If your car’s economy is listed in miles per gallon (mpg), the calculation depends on whether it is imperial or US mpg. UK vehicle figures are generally shown in imperial mpg. Convert miles per gallon to litres per mile using:

Litres needed = journey miles ÷ mpg × 4.546

If you have a reliable estimate in litres per 100 kilometres (L/100km), use:

Litres needed = journey kilometres × L/100km ÷ 100

For a round trip, include the return distance. Add likely detours if you already know about them, and treat the result as an estimate rather than a guarantee.

How to Compare Fuel Costs Before a UK Autumn Drive

Turn fuel use into an estimated trip cost

Once you have an estimated number of litres, multiply it by the price per litre at the station you are considering:

Estimated fuel cost = litres needed × price per litre

Make sure the price is in pounds per litre. For example, a displayed price of 150p per litre is £1.50 per litre. The result estimates the fuel used for the journey at that price; it is not necessarily the amount you will spend at the pump, because you may start with fuel already in the tank or buy more than the journey requires.

For a fair comparison, use the same route distance and fuel economy for each station. Change the price and add any extra distance needed to reach the forecourt. That makes it easier to see whether a cheaper litre price offsets the added driving.

Check current prices near your route

Forecourt prices vary by station and location, and they can change. Look up current petrol or diesel prices close to your starting point, destination and planned route shortly before you travel. Compare stations that are genuinely convenient to reach, including any extra miles or kilometres required to leave and rejoin your route.

The Competition and Markets Authority (CMA) publishes road fuel price transparency information and monitoring material for UK petrol and diesel markets. Its material can help readers understand the market and its monitoring, but it does not replace checking the current price at a particular forecourt. Confirm the displayed price with a current station listing or directly with the station when possible.

Compare like with like: petrol with petrol, or diesel with diesel. Also check whether the listed price is for the fuel grade you need. A headline price for another grade will not give you a useful estimate for your car.

Compare the full journey, not just the pump price

A lower price per litre can still lead to a higher overall journey cost if reaching the station adds a long detour. Include the distance to the station and back to your route in your fuel-use estimate. If the detour is substantial, account for the added fuel for that distance too.

Consider the route as a whole. A convenient station near a planned stop may be a better choice than a cheaper one that sends you away from your route. If you have several plausible options, calculate an estimate for each using its current price and the full distance you would drive.

Keep the estimate in perspective

Fuel economy figures are guides. Autumn weather, colder starts, traffic, roadworks, hills, vehicle condition and how heavily the car is loaded can affect consumption. A route planner’s distance is also an estimate, and your journey may change along the way.

Prices shown online may be delayed or may not reflect the pump when you arrive. Check the price close to departure, and allow some flexibility in your budget for changing conditions. If your car’s dashboard or trip computer provides a recent average fuel economy, it may give a more useful starting point than a general published figure, though actual use can still differ.

Before setting off, check the route distance, your vehicle’s recent fuel economy and the latest nearby forecourt prices. Rechecking those three inputs is the simplest way to make a sensible comparison for your autumn drive.

Source: Competition and Markets Authority

Context & actions About this article

Source check Price and cost method

The calculation estimates fuel used from route distance and vehicle economy; forecourt prices and real-world consumption can change.

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