The transport sector is one of the major contributors to greenhouse gas emissions. This study investigated three greenhouse gases emitted from road transport using a probe vehicle: CO₂, N₂O and CH₄ emissions as a function temperature. It should be highlighted that methane is a greenhouse gas that similarly to carbon dioxide contributes to global warming and climate change. An oxidation catalyst was used to investigate CO₂, N₂O and CH₄ GHG emissions over a real-world driving cycle that included urban congested traffic and extra-urban driving conditions. The results were determined under hot start conditions, but in congested traffic the catalyst cooled below its light-off temperature and this resulted in considerable N₂O emissions as the oxidation catalyst temperature was in the N₂O formation band. This showed higher N₂O during hot start than for diesel fuel and B100 were compared. The B100 fuel was Fatty Acid Methyl Ester (FAME), derived from waste cooking oil, which was mainly RME. A multifunctional additive package was added at 800 ppm to control fuel injector deposit formation. GHG emissions were monitored using an on-board heated Temet FTIR exhaust emission analyzer. A Horiba onboard emissions-measuring system was also used to measures the exhaust mass flow rate together with air/fuel ratio. 172 g/km was the certified CO₂ value based on the standard test cycle and in the real-world driving the vehicle's CO₂ was similar. Methane emissions were negligible, and N₂O emissions were higher than for SI engines with a TWC, which was not expected, but this was due to the lower catalyst temperatures and the more frequent occurrence of stop/start events in congested traffic.