Complex sentence: Most present-day vehicles that run on gasoline are fitted with a "three way" converter, so named because it converts the three main pollutants in automobile exhaust: carbon monoxide, unburned hydrocarbon and oxides of nitrogen.
Split into simpler sentences: Most present-day vehicles that run on gasoline are fitted with a "three way" converter, so named because it converts the three main pollutants in automobile exhaust. The three main pollutants are carbon monoxide, unburned hydrocarbon and oxides of nitrogen.