The development of cost-effective technologies for the treatment of water contaminated by petrochemicals is an environmental priority. This issue is of paramount importance for countries like Saudi Arabia owing to its scarce water resources. Of particular concern are automobile fuels, such as gasoline and diesel, that can contaminate water aquifers from leaking underground fuel storage tanks. Owing to the cost-effectiveness of adsorption-based technologies, low-cost high surface-area commercial activated carbon was used for the adsorptive removal of contaminants from the emulsified fuel-contaminated water. Batch equilibrium experiments showed a high efficacy of the adsorbent. Even with small amounts of the adsorbent, a removal efficiency of more than 97% was obtained for both gasoline as well as diesel. Three different well-known batch adsorption isotherm models, namely the Langmuir, Freundlich, and Temkin, were used for describing the experimental data. The best results were obtained using the Freundlich isotherm followed by the Langmuir model. The maximum capacity was found to be 8.3 g gasoline and 9.3 g diesel per gram of the adsorbent at ambient conditions for a neutral contaminated aqueous solution.