## 6 Conclusions  
The differences in the application of CBA methodologies in the examined countries are significant. The amount of CO\({}_{2}\) emissions calculated by applying the CBA methodology in the Slovak Republic is 1.8% lower compared to the CBA methodology in Austria and 57.9% higher compared to the CBA methodology in the Czech Republic. When the GHG emissions are expressed in terms of CO\({}_{2}\)es, the amount in Slovakia is 6.03% higher than in the Hungarian methodology and 55.1% higher than in the Czech methodology. The differences are even more pronounced in terms of GHG costs. The climate change costs are 9.11 times higher in the CBA methodology in Slovakia than in Hungary, 3.825 times higher than in the Austrian methodology, and 1.871 times higher than in the Czech methodology for the model of road freight transport. These differences are related to the disparities that have already been analyzed and identified in the CBA methodologies. For GHG emissions and the calculation of the change in GHG emissions, the current CBA methodology in the Slovak Republic also considers indirect emissions for electricity (WT approach) but does not consider indirect emissions for other fuels. The same approach should also be applied to other fuels, where currently only direct GHG emissions based on fuel consumption by road transport vehicles during their operation are considered (TtW approach). Indirect (WT) GHG emissions expressed in eCO\({}_{2}\) represent a significant proportion of the total emissions produced from the operation of road transport vehicles, and their inclusion in the total GHG emissions represents an objectified approach that has been applied in transport practice for more than 10 years. For example, the declaration of energy consumption and GHG emissions according to EN 16258 at the company level for the operation of specific vehicles, the transport of specific groups of goods by road freight transport, and the transport of passengers by passenger transport on specific transport routes has been used by transport, freight forwarding and logistics organizations in European countries, including the Slovak Republic, for several years. If indirect GHG emissions from fuel consumption were also considered in the CBA methodology (similar to electricity), the change in total GHG emissions and the value of the associated external costs would be higher. WtT GHG emissions are 15.8% for petrol, 17.69% for diesel, 12.7% for CNG, and 10.4% for LPG of the total GHG emissions according to EN 16258. A new ISO 14083 standard is also in effect from March 2023. WtT GHG emissions are 16.71% for petrol, 15.24% for diesel, 22.07% for CNG, and 17.79% for LPG of the total GHG emissions according to ISO 14083. The CBA methodology should be regularly updated to respond to changes in EU legislation, to changes in ISO and EN standards, as well as to the requirements of newly adopted ISO and EN standards related to pollutant emissions, GHG emissions, emission factors and their economic evaluation. In the future, the implementation of indirect emissions of other pollutants and their associated costs in the CBA methodology will also need to be considered; real transport practice at the company level already applies the declaration of indirect pollutant emissions in addition to GHG emissions (e.g., the EcoTransIT emission and energy calculator). In the future, the methodology updates should also respond to the changes in the structure of sales and operation of vehicles by additional types with respect to the type of fuel used, and emission factors for additional fuels should also be implemented in the methodology. Sources of information on parameter values are given in the relevant chapters of this study. The categories of road vehicles should be standardized when considering the changes in the amounts of individual pollutants and greenhouse gases. In the case of extending the categories of road vehicles, using the same categorization for both pollutant emissions and GHG emissions and associated external costs is recommended.