Various plant-derived alternative fuels have been proposed in recent years as ways to curb the global warming that occurs from the CO2 that is emitted by internal combustion engines. One such fuel is bioethanol. In Brazil, flexible fuel vehicles (FFV) are used that can run on blends from 100% hydrous ethanol (E100) to gasoline containing 22% ethanol (E22). This research addresses the optimal specifications of a FFV engine. FFV engines use E100 and E22 in any ratio. E100 has a very high RON of approximately 110, while that of E22 is low at approximately 95. The researchers considered these characteristics when selecting a compression ratio capable of providing good performance at any ethanol blend ratio. Additionally, ethanol is a single-component fuel without low-boiling-point components, so it has poor combustion at low temperatures. In general, FFV engines are often built with one intake valve to enhance product usability at low temperatures. To achieve both combustion at low temperatures and high output, the researchers chose a VTEC mechanism with one intake valve shut off. In addition, a new engine control, built especially for FFV, was used to enhance product usability at low temperatures when using E100. Using the above technologies, an engine was built specifically for FFV that offers both output and product usability when using E100. This paper is an introduction to these technologies.