Most fuel cost calculators ask you to enter your MPG manually. But how many drivers actually know their car's real-world fuel economy off the top of their head? Save at the Pump's fuel cost calculator now lets you look up your car by registration plate instead, automatically identifying your fuel type and estimating your MPG from your engine size. Here is how it works and what it can tell you about your annual fuel spend.
How does the registration plate lookup work?
When you enter your registration number, Save at the Pump queries the DVLA's Vehicle Enquiry Service in real time. This is the same official government database used to check MOT status and tax. It returns your vehicle's make, year of manufacture, fuel type and engine capacity.
From the engine capacity and fuel type, the calculator estimates your real-world MPG. For example, a 1.6 litre petrol engine built after 2010 typically achieves around 38 MPG in real-world driving. A 2.0 litre diesel typically achieves around 44 MPG. These are conservative estimates based on real-world driving rather than the optimistic figures manufacturers quote in lab conditions.
The estimated MPG is pre-filled in the calculator but you can adjust it if you know your actual figure. The most accurate way to find your real-world MPG is to fill up completely, reset your trip meter, drive normally until you need to refuel, then divide the miles driven by the litres used (multiplied by 0.2199 to convert to gallons).
What does the calculator show you?
Once your vehicle details are filled in, the fuel cost calculator shows:
- Your annual fuel cost based on your mileage and local prices
- Your cost per mile
- How much you could save by using the cheapest nearby station instead of the most expensive
- The difference in annual spend between your current MPG and a more efficient car
How much does the average UK driver spend on fuel?
According to NimbleFins analysis of Department for Transport data and April 2026 fuel prices, the average UK petrol car driver spends around £1,164 per year on fuel. Diesel drivers spend more, around £1,548 per year, partly because they tend to drive higher annual mileages.
These figures are based on the average UK annual mileage of 7,100 miles per year for petrol cars and 8,300 miles for diesel, using fuel prices from early April 2026. Costs have risen compared to late 2025 due to the Middle East conflict pushing oil prices higher.
How does your car affect your annual fuel bill?
Engine size and fuel type have a significant impact on how much you spend. Here is a comparison of typical annual fuel costs at current prices, assuming 7,100 miles per year:
| Car type | Real-world MPG | Annual cost (7,100 miles) |
|---|---|---|
| Small petrol (under 1.0 litre) | 52 MPG | £893 |
| Family petrol (1.4-1.8 litre) | 38 MPG | £1,221 |
| Large petrol (over 2.5 litre) | 24 MPG | £1,934 |
| Family diesel (1.6-2.0 litre) | 44 MPG | £1,549 |
| Large diesel (over 2.0 litre) | 36 MPG | £1,893 |
How much can you save by choosing cheaper fuel?
In most UK areas, prices vary by 8-12p per litre between the cheapest and most expensive station within 10 miles. On 7,100 miles per year at 38 MPG, you use approximately 848 litres of fuel. A saving of 10p per litre across those 848 litres saves you £84.80 per year — just by choosing where you fill up.
Use our live fuel price map to find the cheapest station near you, updated every hour from official Government data. Combined with the fuel cost calculator, you can see exactly how much your choice of station affects your annual spend.
Try the fuel cost calculator by registration
Enter your registration plate at saveatthepump.co.uk/fuel-cost-calculator. Your vehicle's fuel type and estimated MPG will be pre-filled automatically. Adjust the mileage to match your typical annual driving and the calculator will show your annual fuel cost and potential savings.