Related by context. Frequent words. (Click for all words.) 62 internal combustion engines 61 combustion engine 61 internal combustion engine 60 internal combustion 60 combustion engines 57 hybrid powertrains 56 reciprocating engines 56 turbocharged engines 56 conventional internal combustion 55 compression ignition 54 diesel engines 54 electric drivetrain 53 gasifiers 53 gaseous fuels 53 particulate filters 53 diesels 53 powerplants 52 Fossil fuels 52 electrically powered 52 diesel engine 52 engines 51 CVTs 51 induction motors 51 electric motors 51 spark ignition 51 gasifier 51 turbo chargers 51 drivetrains 51 hybrid drivetrain 51 electrically driven 51 fossil fuels 51 electric propulsion 51 hydraulic pump 51 piston engine 51 combustion 50 cleaner quieter 50 air conditioning compressor 50 motors 50 nonpolluting 50 diesel powered 50 AGVs 50 Li ion batteries 50 genset 50 electric powertrain 50 microturbines 50 dry sump 50 NiMH batteries 49 V6 petrol 49 diesel 49 rotary engine 49 FFVs 49 variable valve 49 Rechargeable batteries 49 5kW 49 compressed hydrogen 48 electric motor 48 turbocharging 48 super capacitors 48 propulsion 48 diesel particulate filters 48 particulate filter 48 superchargers 48 NGVs 48 FCVs 48 Audi e tron 48 flywheels 48 hydrogen 48 V6s 48 ECUs 47 autogas 47 Fischer Tropsch 47 hydraulic steering 47 combustion turbines 47 Lithium ion battery 47 electric powertrains 47 fossil fuel 47 electrolyzer 47 Lithium Ion batteries 47 diesel particulate filter 47 boilers 47 PEM fuel 47 Audi R# 47 electrics 47 aftertreatment 47 efficient powertrains 47 speed automatics 47 drivelines 47 Carbon dioxide emissions 47 hydrogen internal combustion 47 gearboxes 47 turbocharged diesel 47 #.# liter HDi 46 cellulosic materials 46 Selective Catalytic Reduction SCR 46 hydraulic fluids 46 polluting fossil fuels 46 BEVs 46 gensets 46 smart fortwo electric 46 compressed air 46 EVs