Despite the development of engines using renewable fuels, the current market still uses internal combustion engines, which in turn use non-renewable fuels (fossil fuels). The internal combustion engines used in land vehicles can be classified into two main groups: the Otto cycle and the Diesel cycle. Because they burn fossil fuels, these engines are relatively closely linked to environmental pollution and oil shortages. The internal combustion engine is one of the biggest contributors to air pollution and the depletion of crude oil reserves. Given these important issues, this study will present a comparison between the Otto cycle engine and the diesel cycle, using two vehicles with the same characteristics, an S10 (Flex) pick-up truck and an S10 diesel pick-up truck. The methodology of this research consisted of experimental trials and tests carried out on a dynamometer and gas analyzer, where the results of performance (torque and power), fuel consumption, and emissions were compared between alcohol, gasoline, and diesel fuels.