Related by context. Frequent words. (Click for all words.) 54 GHGs 54 pollutant emissions 54 emission 54 greenhouse gas 54 greenhouse gas emissions 53 greenhouse gases 53 emissions 53 tailpipe emissions 53 carbon dioxide emissions 53 greenhouse gas emission 52 carbon dioxide emission 51 GHG emissions 51 greenhouse emissions 50 CO2 emission 50 GHG reduction 50 carbon emission 50 greenhouse gasses 50 GHG 50 global warming gases 50 CO2 emissions 49 carbon emissions 49 exhaust emissions 48 heat trapping emissions 48 CO2 48 greenhouse gas GHG emissions 48 emission reductions 48 emission reduction 48 CAFE standards 48 nitrous oxide emissions 47 Carbon dioxide emissions 47 greenhouse gas GHG 47 carbon emitting 46 alternative fuels 46 reducing carbon emissions 46 carbon dioxide CO2 emissions 45 carbon dioxide 45 curbing greenhouse gases 45 pollutant 45 particulate emissions 45 automobiles 45 cleaner fuels 44 Emissions 44 greenhouse gases emitted 44 automakers 44 pollution 44 renewable fuels 44 C# emissions 44 fossil fuel 44 greenhouses gases 44 fuel 44 biofuels 44 reduce carbon emissions 44 Greenhouse gases 43 diesel 43 air pollution 43 reducing CO2 emissions 43 Fuel Efficiency 43 heat trapping carbon dioxide 43 carbon dioxide CO2 43 carmakers 43 combustion 43 NOx emissions 42 NOx 42 emission norms 42 Fuel Economy 42 fossil fuels 42 biofuel 42 environmental 41 carbon emitted 41 zero emission 41 nitrogen oxide emissions 41 internal combustion engine 41 efficiency 41 pollutants 41 bio fuels 41 PHEVs 41 greenhouse gas emitters 41 regulate greenhouse gases 40 internal combustion 40 powertrains 40 heat trapping gases 40 Greenhouse Gas 40 polluting 40 curbing greenhouse gas 40 Dave McCurdy 40 automobile 40 reducing greenhouse gas 40 mercury emissions 40 reduce greenhouse gas 40 nonpolluting 40 carbon emitters 40 combustion engines 40 climate change 40 Emission 40 cleaner burning 40 carbon dioxide methane 40 CO2 emitted 39 Ghosn 39 carbon 39 ethanol blends 39 HEVs