Cost benefit analysis of three different urban bus drive systems using real driving data

•Cost benefit analysis of city bus propulsion systems (diesel, hybrid, CNG).•Ex-ante and Ex-post CBA results after three years of exploitation compared.•Real-world driving exhaust emissions data used, including PM10 measurements.•External costs from pollution (NOX, CO, CO2, PM10 and noise) assessed.•CNG alternative most attractive in terms of economic and environmental incentives.