An unprecedented study reveals that almost 30% of the samples analyzed in Brazil were adulterated; volumetric fraud leads the infractions
Fueling the vehicle has become a risky task in several regions of the country. An unprecedented survey carried out by the Legal Fuel Institute (ICL), through the “Mystery Shopper” project, revealed that 28% of the samples collected around the country in 2025 had some type of irregularity. The study, which visited gas stations in 14 states, used uncharacterized vehicles to obtain 3,210 samples of gasoline, ethanol and diesel, drawing a heat map of fraud in Brazil.
The data show that volumetric fraud – when the pump dial indicates a quantity higher than what actually enters the tank – leads the infractions, with 324 cases registered. It is the simplest and most common adulteration, harming the consumer immediately.
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In addition to the direct financial loss at the pump, chemical adulterations are a concern for their sophistication and mechanical damage. Cases of gasoline with ethanol content above the legal limit (30%) and diesel with low biofuel content were recurrent. Such practices result in loss of performance and increased consumption, symptoms that the attentive driver can perceive on a daily basis.
The scenario of insecurity worsened after Operation Hidden Carbon, launched by the Federal Police. The investigations exposed the participation of organized crime in the distribution chain, introducing methanol — a highly toxic substance — into the fuel mixture. At inspected points in São Paulo, for example, compounds with 95% methanol and only 5% gasoline were found.
The severity of the problem transcended the automotive sector in the second half of 2025, when diverted methanol was detected even in alcoholic beverages, causing hundreds of hospitalizations and deaths. In view of this, the ICL categorized the analyzed regions into “risk zones”.
Cities such as Rio de Janeiro, Curitiba and São Bernardo do Campo appear with critical signage on heat maps, indicating a high probability of irregularities.
