The technical name for the gas-powered engine in most cars, SUVs, and trucks. It generates power by igniting an air-fuel mixture within a cylinder that forces down a piston. The number of cylinders in most modern engines varies from three all the way up to twelve, and engines can be enhanced with forced induction devices, called turbochargers and superchargers, that force more air into a cylinder to generate extra power. The byproduct of this power generation, however, are harmful emissions like hydrocarbons, oxides of nitrogen (NOx), carbon monoxide (CO), as well as carbon dioxide (CO2).