The article discusses how hybrid technology is being used in buses to reduce emissions and fuel consumption. There are two main types of hybrid systems: series and parallel. In the series system, the engine powers a generator that creates electricity to propel the bus or recharge its batteries. This technology makes buses quieter, cleaner, and cheaper to operate. Hybrid buses are seen as a more advanced fuel technology compared to other options like compressed natural gas or methanol. The smaller engines used in hybrid buses result in lower emissions and operating costs, making them a popular choice in the mass transit industry.