How to Compare UK Petrol and Diesel Prices Before a Long Drive

Fuel prices can vary between forecourts, so a UK-wide average is a useful starting point, not a quote for the station you will use. Before a long drive, compare the same fuel type near home, work and along your route, then weigh any saving against the cost and time of a detour. A simple calculation can help you estimate journey fuel costs, but the result depends on your actual fuel economy and the price you pay.

Use the RAC average as a benchmark

RAC Fuel Watch publishes average UK petrol and diesel prices. Use those figures to understand the broader price level and compare changes over time. They do not tell you what a specific forecourt is charging today.

A station’s price can differ from the national average. Treat the average as context, then check local prices directly before choosing where to fill up. The RAC page is useful for the national picture; current station information is needed for a local decision. The distinction matters when budgeting: multiplying a national average by your estimated litres gives an indicative figure, not a confirmed bill.

Compare like-for-like prices near you and along the route

Start by checking forecourts near places you already visit, such as home or work. Then look at stations near your route or destination. Compare petrol with petrol and diesel with diesel, and make sure the listed grade suits your vehicle. A lower figure for a different fuel type is not a meaningful comparison.

For each option, check the price per litre, how far it is from your route, and whether the listed price is recent. Practical details can also affect the choice, including opening hours and whether the station is accessible on your side of the road. A station that appears nearby on a map may still require extra driving to reach and rejoin your route.

Prices can change, and a listing may not reflect what is on the pump when you arrive. Check the station’s current price before setting off, and confirm it at the forecourt. If a price cannot be verified as current, treat it as a lead rather than a guaranteed saving.

Include the detour in the comparison

A lower price per litre does not automatically mean a cheaper stop. Estimate the extra distance to reach the forecourt and return to your route, then account for the fuel your vehicle will use on that detour. Consider the extra time as well, particularly if the station is off a busy road or likely to have queues.

The amount you plan to buy affects whether a small price difference adds up to a worthwhile saving. If two stations have similar prices, the one already on your route may be the more practical choice. The useful comparison is the total cost of obtaining the fuel, including the added driving, rather than the pump price alone.

Estimate journey fuel with your real-world economy

Use your vehicle’s typical fuel economy from ordinary driving rather than relying only on an advertised figure. Your actual consumption can vary with speed, traffic, load, weather and driving style, so treat the result as an estimate. The calculation gives you a planning figure; it cannot account precisely for conditions on the day.

For a vehicle measured in miles per gallon (mpg), estimate litres needed with this calculation:

Distance in miles ÷ real-world mpg × 4.546 = estimated litres

Then calculate the fuel cost:

Estimated litres × price per litre = estimated journey fuel cost

For example, a 300-mile journey in a car averaging 40 mpg would use about 34.1 litres: 300 ÷ 40 × 4.546. At a hypothetical price of £1.50 per litre, the fuel would cost about £51.15. This is an illustration, not a current UK price or a quote for any station. To estimate a round trip, use the full return distance.

If you expect heavy traffic, carry extra weight or drive through hilly areas, allow for consumption to differ from your usual figure. You can compare costs at different local prices by using the same estimated litres for each one; keep the distance and economy assumptions unchanged so the price comparison stays like-for-like.

Make the check before you leave

Before a long drive, use RAC Fuel Watch to see the national average, compare current local prices for the correct fuel, and check stations near your route. Recheck the chosen forecourt’s price shortly before departure, then decide whether any detour is worthwhile using your vehicle’s real-world economy. The national average helps set context; the current pump price and the full cost of reaching it determine what you are likely to spend.

Source: RAC