Emissions for the different vehicles (diesel and natural gas; hydrogen fuelled fuel cell vehicles emit no harmful emissions) were calculated using two tools, Copert  for Diesel vehicles and Mobile 6  for CNG vehicles.
Consumption, mileage values and vehicle characteristics where obtained directly from STCP.
3.2.1. Hydrogen Vehicles
For the hydrogen vehicles an autonomy of 200km was accepted with the consumption of 40 kg of hydrogen (reference value suggested by DaimlerChrysler, road test confirm this value as a good estimate) . Final energy consumption is 23,9 MJ/km.
3.2.2. Diesel Vehicles
For Diesel vehicles, the results for a Euro III vehicle are presented in Table 13.
Table 13. Results for a Euro III diesel bus operating in regular service in Porto.