Fuel consumption of diesel, natural gas, hybrid, full electric and hydrogen fuel cells based buses: A simulated comparison using standard road cycles and gradeability tests

Due to the detrimental environmental impact of diesel and gasoline vehicles, alternative propulsion technologies—such as hybrid electric, battery electric, and fuel cell vehicles—have garnered increased attention. However, no studies were found that analyse both gradeability and fuel consumption across varying road inclines for different bus types—diesel, compressed natural gas (CNG), hybrid electric, battery electric, and fuel cell—while considering the impact of A/C operation. Additionally, limited research has addressed the influence of critical factors, such as bus weight, drag coefficient, and wheel radius, on fuel consumption for these buses. This study addresses this gap by evaluating the fuel consumption and gradeability of five bus types (diesel, CNG, hybrid electric, battery electric, and fuel cell) using the MATLAB/Simulink-based ADVISOR tool. Fuel consumption was analysed over the Orange County Transit Authority (OCTA) drive cycle under both A/C on and off conditions, and the effects of key vehicle parameters—bus weight, drag coefficient, and wheel radius—were investigated. Fuel consumption was also assessed on the modified Central Business District (CBD-14) drive cycle at 0 %, 2 %, and 4 % road grades. Gradeability tests were conducted at 20 and 40 km/h. In gasoline equivalent, the battery electric bus exhibited the lowest fuel consumption (29.9 L/100 km with A/C off and 38.4 L/100 km with A/C on), while the CNG bus showed the highest values (87.3 L/100 km with A/C off and 106.9 L/100 km with A/C on). Among the examined parameters, bus weight had the greatest impact on fuel consumption, whereas drag coefficient was the least influential. For a 2 % road grade, the fuel cell bus experienced the largest increase in consumption (78 % with A/C off; 35.5 % for the electric bus with A/C on), while the hybrid electric bus showed the smallest increase. In gradeability tests, the hybrid electric bus achieved the highest climbing capability—22.5 % at 20 km/h and 10.3 % at 40 km/h (A/C off)—compared to the fuel cell bus, which reached only 12.2 % and 7.0 %, respectively; similar trends were observed with A/C on. These findings provide valuable insights into the operational efficiency of different bus technologies under real-world driving conditions.