Studies report differences in performance for vehicles of similar technology, suggesting that variables affect energy consumption, such as operating conditions. This work seeks to determine the energy consumption of a fleet of 8 diesel buses under real operating conditions in Chile. This fleet was monitored using a commercial telemetry system for over three months, with data obtained at 1/15 Hz of location, speed, engine RPM, and energy consumption. As a result, an average consumption of 0.430 L/km and a weighted average consumption of 0.417 L/km were obtained for diesel buses. In this case, accelerations and variations in altitude were the variables that most affected energy consumption. Finally, a mixed typical driving cycle (urban and highway) was determined.