Fuel pump discrepancies exceeding tank capacity aren’t necessarily fraud, as technical factors explain many cases.
Tank Capacity vs. Pumped Fuel
Many drivers have experienced situations where their car’s tank holds 69 liters according to manufacturer data, but the pump shows over 70 liters even with 6-8 liters already in the tank.
Technical specifications indicate approximate tank capacity, with manufacturers accounting for an “air cushion” above the fuel plus fuel in the lines. Slow refilling can minimize or eliminate this air cushion, with tests showing up to 20% more fuel than nominal capacity.
Pump Accuracy Issues
Problems occur when pumps show more fuel than actually enters the tank. NIK controls found significant supervision gaps, with irregularities at 4 of 28 stations (14.3%).
Over 60% of tested pumps at these stations overread by 4.3% to 5.6%, meaning a driver could get a liter less when pumping 20 liters.
Fuel Quality Testing 2025
From January 13 to December 31, 2025, Trade Inspection tested 1,787 fuel samples. 24 samples failed to meet required standards, with diesel fuel performing worst (19 of 24).
Regional variations were noted, with the most cases in Mazowieckie Voivodeship. In Borkowo, sulfur content in diesel exceeded the norm by over 20 times.
How Poor Fuel Quality Damages Engines
For diesel, key factors include oxidation stability, ignition temperature, water content, sulfur, and contaminants. Low stability causes cloudiness and resin deposits that clog filters and injectors.
Water leads to corrosion, while excess sulfur accelerates engine wear and increases sulfur oxide emissions. For gasoline, octane number and vapor pressure are critical.
What to Do If You Suspect Fraud
File a report with UOKiK if you suspect violations of collective consumer interests. You can reference the Act on Measures and the Act on the System for Monitoring and Controlling Fuel Quality.
For engine damage, commission an independent workshop evaluation and consider civil claims. Multiple complaints about a station increase the chance of unannounced inspections.