A　total　of　15　light-duty　diesel　vehicles　(LDDVs)　were　tested　with　the　goal　of　understanding　the　emission　factors　of　real-world　vehicles　by　conducting　on-board　emission　measurements.　The　emission　characteristics　of　hydrocarbons　(HC)　and　nitrogen　oxides　(NOx)　at　different　speeds,　chemical　species　profiles　and　ozone　formation　potential　(OFP)　of　volatile　organic　compounds　(VOCs)　emitted　from　diesel　vehicles　with　different　emission　standards　were　analyzed.　The　results　demonstrated　that　emission　reductions　of　HC　and　NO,,　had　been　achieved　as　the　control　technology　became　more　rigorous　from　Stage　I　to　Stage　IV.　It　was　also　found　that　the　HC　and　NO　emissions　and　percentage　of　O-2　dropped　with　the　increase　of　speed,　while　the　percentage　of　CO2　increased.　The　abundance　of　alkanes　was　significantly　higher　in　diesel　vehicle　emissions,　approximately　accounting　for　41.1%-45.2%,　followed　by　aromatics　and　alkenes.　The　most　abundant　species　were　propene,　ethane,　n-decane,　n-undecane,　and　n-dodecane.　The　maximum　incremental　reactivity　(MIR)　method　was　adopted　to　evaluate　the　contributions　of　individual　VOCs　to　OFP.　The　results　indicated　that　the　largest　contributors　to　O-3　production　were　alkenes　and　aromatics,　which　accounted　for　87.7%-91.5%.　Propene,　ethene,　1,2,4-trimethylbenzene,　1-butene,　and　1,2,3-trimethylbenzene　were　the　top　five　VOC　species　based　on　their　OFP,　and　accounted　for　54.0%-64.8%　of　the　total　OFP.　The　threshold　dilution　factor　was　applied　to　analyze　the　possibility　of　VOC　stench　pollution.　The　majority　of　stench　components　emitted　from　vehicle　exhaust　were　aromatics,　especially　p-diethylbenzene,　propylbenzene,　m-ethyltoluene,　and　p-ethyltoluene.　(C)　2016　The　Research　Center　for　Eco-Environmental　Sciences,　Chinese　Academy　of　Sciences.　Published　by　Elsevier　B.V.