Detection of adulteration in the petroleum fuels (gasoline and diesel) is challenging because the adulterants usually include those compounds which are already present in these fuels. Measurements of various physico-chemical properties are employed in addition to chromatography and spectroscopy for determining the compositional variations of these fuels. It is required to ensure their compliance with the regulatory specifications. The inclusion of statistical design and data treatments certainly provide enough sensitivity to discriminate adulterated and unadulterated samples in the case of gasoline. On the contrary, discrimination of diesel from its adulterants is difficult which demands rigorous analytical strategies and unequivocal data interpretation.