In developed countries, vehicle manufacturers have included flex-fuel technology. However, high-mileage vehicles lacking this technology are more prevalent in certain regions of the world. The present research will focus on the potential of ethanol, particularly its feasibility of implementation in conventional cars. To provide information about the benefits, this work investigates the impact of various concentrations in an engine that was initially designed for gasoline. The procedure for converting to ethanol-gasoline is outlined, along with a comparison of wheel horsepower, cost, and emissions. Tests were conducted in controlled environments using certified equipment, such as a dynamometer and emissions verifier, to calibrate the engine computer and optimize the properties of each fuel. The use of low concentrations of ethanol (E10) can be implemented in any engine that uses electronic fuel injection. Using higher concentrations of ethanol, along with necessary vehicle modifications in both hardware and software, results in considerable increases in power (up to 20% and, on average, 10% with E75) and a decrease in most pollutants (37.8% HC, 27.17% CO, and 15.71% CO2 with E75). To achieve this, a fuel injection increase of 22–43% and a global ignition advance of 3.1–3.2° relative to G100 were observed. Analysis of the vehicle fleet circulating on Mexico’s road network indicates a 24.6% higher consumption of E75, representing an additional 7.82 billion liters in 2023. However, the cost factor indicates a contrary trend, a saving of $77.61 billion Mexican pesos. This saves the user $2955 Mexican pesos annually, making the initial investment more appealing.