NGVs connect to natural gas pumps with tightly fitting connections that prohibit refueling losses. The fuel system in a NGV does not leak during normal operation. A natural gas vehicle's fuel is stored under pressure. If it leaked, fuel would escape rapidly and the problem would need quick repair for the vehicle to continue to operate. Also, the tank, hoses, and components in a NGV are thicker and tighter fitting than their gasoline counterparts.
Evaporative emissions are virtually non-existent in NGVs.
In addition, NGVs' exhaust emissions are less than emission from unleaded gasoline vehicles. When comparing NGVs to gasoline vehicles, natural gas vehicles emit lower amounts of VOCs and slightly higher amounts of NOx. NGVs are ideal for an urban setting. Liquid petroleum gas is derived from natural gas processing and must have at least a 90 percent propane content. As in NGVs and for the same reason, evaporation losses do not exist.