Brazil was drawing a lot of world attention at the time due to the production of flex-fuel vehicles introduced by its own automobile industries since 2003. Today the fleet of flexible-fuel vehicles in Brazil are the largest in the world with 23 million vehicles (ANFAVEA, 2015), following the United States with 11 million units (EIA, 2015), Canada with one million units (TPSGC , 2015), and Europe, led by Sweden with 229,400 units (BAFF, 2015). There are over 80 flex car and truck models available in Brazilian manufactured market by 14 major automakers. Brazilian flexible-fuel vehicles are optimized to run on any mix of gasoline and up to 100 percent hydrous ethanol. The flexibility in the choice of fuel gives a comparative advantage to this vehicle type. Different to other works done in this subject, this study seeks to value this advantage for five Brazilian geographic regions: Northern, Northeastern, Central-Western, Southeastern and Southern, determining the value of this flexibility for each region. For this purpose, fuel prices were considered as stochastic variables following a mean reversion stochastic process. Monte Carlo simulation has been utilized to predict the prices, and real options theory and a fuzzy algorithm applying triangular fuzzy Numbers (TFN) to value embedded flexibility. Since TFN offer good performance and computational efficiency and provide a more realistic modeling of the problem, they were used to model the fuel consumption rates and the distance traveled by vehicles. The results indicate that the option of flexibility adds more significant value to the owners being in Southeastern, Central-Western, and Southern regions.