The article studies two types of hybrid vehicles - one that uses a mix of electricity stored in a battery and hydrogen (FC-PHEV), and another using hydrogen and a battery (FC-EREV). The goal was to compare their performance, range, and emissions to see how they can help reduce greenhouse gases in road transport. The researchers created a test to simulate real-world conditions and found that these hybrid vehicles can travel longer distances and emit fewer greenhouse gases compared to regular cars. This means these hybrids could be a good solution for reducing emissions, even before we have enough hydrogen refueling stations.