Related by context. Frequent words. (Click for all words.) 75 internal combustion engine 72 internal combustion engines 67 combustion engine 61 combustion engines 56 electric motor 56 diesels 56 diesel engine 55 electric propulsion 55 turbocharging 55 hybrid powertrain 55 diesel engines 54 electric motors 51 powerplants 51 combustion 50 fossil fuels 50 diesel powered 50 rotary engine 50 hybrids 50 naturally aspirated 50 V8 engine 49 turbos 49 turbocharged 49 manual gearbox 49 electrically powered 49 turbo diesel 49 motors 49 drivetrain 48 powertrain 48 normally aspirated 48 PHEVs 48 propulsion 47 fossil fuel 47 hybrid electric 47 liter V# 47 hybrid 47 turbodiesel 47 #.#L [001] 47 powerplant 47 #.# liter V8 47 hydrogen powered 47 PHEV 46 engined 46 #hp [002] 46 powertrains 46 horsepower 46 hp 46 engines 46 hydrogen 46 Volt 46 gas guzzling 46 cylinder engine 46 diesel 45 cylinder engines 45 automatics 45 nonpolluting 45 ZR1 45 pistons 45 battery powered 45 V8s 45 EVs 45 turbo 45 Hybrids 45 V8 engines 45 flywheels 44 cylinder diesel 44 locomotion 44 V# engine 44 cylinder petrol 44 hydrogen fuel 44 V8 powered 44 electric hybrid 44 Li ion 44 exhaust emissions 44 carburetors 44 zero emission 44 Diesels 44 carbon emitting 43 V6 engine 43 Hybrid 43 Smart Fortwo 43 automobiles 43 ultracapacitors 43 supercharger 43 nickel metal hydride 43 manual transmissions 43 Chevy Volt 43 #hp [001] 43 bio ethanol 43 turbocharger 43 liquid cooled 43 twin turbo 42 EcoBoost 42 liter turbo 42 variable valve timing 42 cylinder 42 roadster 42 roadsters 42 automatic transmissions 42 Li ion batteries 42 gearboxes 42 V8