Related by context. Frequent words. (Click for all words.) 56 CAFE 53 tailpipe emissions 47 mpg 47 Fuel Economy 41 gas guzzlers 40 regulate greenhouse gases 40 SUVs 40 g km 40 gas guzzler 39 carbon dioxide emissions 39 exhaust emissions 39 renewable fuels 39 Waxman Markey 39 greenhouse gas emission 39 emissions 38 gas guzzling 38 reduce carbon emissions 38 alternative fuels 38 greenhouse gases 38 mileage 38 greenhouse gas 38 greenhouse gas emissions 38 CO2 emissions 37 automakers 37 heat trapping gases 37 greenhouse emissions 37 GHGs 37 greenhouse gasses 37 diesel 36 CARB 36 Clunkers 36 global warming gases 36 electric hybrids 36 NHTSA 35 diesels 35 Automakers 35 Clunkers program 35 subcompact 35 Kyoto accord 35 gallon 35 carbon dioxide CO2 emissions 35 ethanol blends 35 greenhouse gas GHG emissions 35 GHG emissions 35 Emissions 35 scrappage 34 emission 34 carbon emissions 34 electric hybrid 34 diesel powered 34 nitrogen oxides 34 CO2 emission 34 mercury emissions 34 gases blamed 34 emission reduction 34 reducing carbon emissions 34 #g/km [002] 34 fossil fuels 34 catalytic converters 34 nitrogen oxide emissions 34 EcoBoost 34 regulate carbon dioxide 33 reduce greenhouse gas 33 cleaner fuels 33 reducing CO2 emissions 33 ozone pollution 33 Kyoto Protocol 33 midsize sedan 33 GHG 33 Clean Air 33 internal combustion engine 33 emission reductions 33 EPA 33 FairTax 33 HFCs 33 Toyota Prius 33 Elantra 32 carmakers 32 Kyoto pact 32 clunkers 32 Autodata Corp. 32 smog 32 flex fuel 32 liter 32 mercury pollution 32 polluters 32 CEO Alan Mulally 32 pollution 31 NOx 31 No Child Left 31 LaNeve 31 nitrogen oxide 31 PHEV 31 Chevrolet Volt 31 #mpg [002] 31 HOV lanes 31 fuel 31 subcompacts 31 Kyoto treaty 31 Kyoto protocol 31 Pipas