目標:車輛配備廢氣再循環系統(ExhaustGas Recirculation， EGR)是有效降低車輛使用NOx 排放量的方案之一;不過，卻缺乏研究探討EGR系統於道路行駛之成效。本研究即探討配備EGR車輛之道路實測NOx排放，並將與推估車輛移動排放NOx總量模式使用的排放係數相互比 較。方法:本研究逕用車裁量測設備(On-BoardEmission Measurement) ，搭載於配備EGR系統之汽油車輛上，進行高速公路與市區道路之實際行駛測試，量測並紀錄逐秒NOx排放率;再進行法規審驗之實驗室測試並紀錄下可比對的數據。結果:前述測試條件下，配備EGR車輛實測之NOx排放係數均低於1g/km '顯著低於國內車輛排放推估模式所採用的排放係數70月毛以上;許多狀況下實測佐尚不及模式排放係數10月毛;而且，車遠大於70km/hr高速區間排放係數隨速 度變化的趨勢實際應為降低，而非模式係數升高。結論:推估模式所使用之NOx排放係數，無法呈現搭載EGR車輛的NOx排放特性。本研究建議應儘速建立配備EGR車輛的NOx排放係數，並掌握其在車輛總數中的占比，才能較為適切的推估車輛排放NOx總量。

Objectives: The Exhaust Gas Recirculation (EGR) system is one solution for reducing vehicle Nitrogen oxide (NOx) emissions; however， there is no research on the effectiveness of the EGR system， particularly with regard to gasoline-engine vehicles. This study aimed to fill in this gap. Methods: This study utilized a gasoline-engine test car equipped with the EGR system and an on-board emission measurement device which recorded second-by-second NOx emission rates during road tests conducted on freeways and urban arterials. Comparable data was recorded from chassis tests performed in the laboratory. Results: NOx emission rates measured from the test car， in all conditions， were less than 1 g/km. This was significantly lower than the parameters set by the EPA model， MOBILE-Taiwan. Moreover， the measured NOx emission rates decreased while vehicular speeds increased over 70 km/hr. This was in contrast with the increasing trend of the parameters from the EPA Model. Conclusions: The results of this study showed that the NOx emission rates of the EGR-equipped vehicle were not well represented by the model parameters. In light of the evidence， this study calls attention to the need for investigation of NOx emission rates of EGR-equipped vehicles in order to better estimate vehicle NOx emission as the popularity of EGR-equipped vehicles in the new car fleet is significant.