How We Validate Fuel Prices
Where the prices come from
Since November 2023, all UK fuel retailers with more than five sites have been required by law to report their pump prices to the government at least every 30 minutes. This data is made available through the UK Government Fuel Finder scheme, which MPG Calc queries continuously throughout the day.
The scheme covers more than 6,500 stations across the UK and is the same underlying dataset used by most fuel price comparison services. The prices reported are set by the retailers themselves.
Why prices sometimes need correcting
While mandatory reporting has dramatically improved price transparency, the data is self-reported and occasionally contains errors. The most common issues we see are:
- Swapped fuel types — a station reports its E5 (super unleaded) price in the E10 (regular petrol) field, or vice versa. Super unleaded is always more expensive than regular petrol, so when these values are transposed, it is straightforward to detect.
- Misfiled diesel prices — premium diesel (SDV) reported in the standard diesel (B7) field, or the reverse. Again, premium diesel is always more expensive, so inversions are detectable.
- Implausible values — prices that are statistically far outside the range of anything currently reported nationally. These may be placeholder values, system defaults, or data entry errors.
What we do about it
Every time we fetch new price data, we run automated quality checks across all stations. Where we can be confident an error is present, we correct it automatically — for example, swapping E5 and E10 prices back to the right fields. In every case, we keep a record of the original submitted value alongside the corrected one.
Where we detect a potential problem but cannot determine the correct value with sufficient confidence, we flag the station's prices as uncertain and exclude them from national and regional averages. The raw submitted prices are still shown on the station's detail page, with a clear warning.
Stations with auto-corrected prices are marked with a ✓ badge. Stations with flagged prices are marked with a ⚠ badge.
How confident should you be?
Our corrections only fire when the statistical evidence strongly supports a specific error type. We prefer to flag and exclude rather than guess when the evidence is ambiguous. The goal is to ensure that the prices used in our averages and station-finder are as accurate as possible, not to modify data unnecessarily.
If you notice a price that looks wrong on a station page, you can let us know and we will investigate.