This study investigated the current practice of English-Medium Instruction (EMI) in the academic field of transportation. Key Performance Indicators (KPIs) of EMI were proposed and analyzed based on the education databases in Taiwan. A multi-year case study compared EMI with Chinese-Medium Instruction (CMI) via quasi-experimental design. The findings are as follows: 1. Seven departments in six universities had 31 EMI courses primarily in the graduate programs. The departments in the public universities fared better on certain EMI indicators, while those in the private ones did better on others. 2. Gender might be a factor of choosing EMI courses. 3. About half of the departments offered EMI courses without English for Specific Purposes (ESP) courses, and vice versa, violating the ideal model of using ESP to sustain EMI. 4. The course evaluation of CMI and EMI classes did not show statistically significant differences in the case study, supporting the continuance of EMI. It is suggested that the transportation departments adopt the one-CMI and one-EMI class model to meet students' needs. Moreover, ESP courses (with more emphasis on English) should be offered to ease students' language phobia. EMI courses, therefore, can focus on content knowledge. The KPIs and case analysis framework proposed in this study are eligible for other fields.