* Spark-ignition engines (gasoline engines): These engines use spark plugs to ignite the air-fuel mixture. They are the most common type of engine in cars and light trucks.
* Compression-ignition engines (diesel engines): These engines use heat from compression to ignite the air-fuel mixture. They are more efficient than spark-ignition engines, but they also produce more emissions. Diesel engines are typically used in heavy-duty trucks, buses, and construction equipment.
* Rotary engines: These engines use a triangular rotor to compress and ignite the air-fuel mixture. They are more compact and lightweight than piston engines, but they are also less efficient. Rotary engines were used in some Mazda vehicles in the 1970s and 1980s.
External Combustion Engines
* Stirling engines: These engines use a closed cycle of heating and cooling to convert heat into mechanical energy. They are very efficient, but they are also complex and expensive to build. Stirling engines have been used in a variety of applications, including generators, pumps, and cars.
* Rankine cycle engines (steam engines): These engines use a boiler to generate steam, which is then expanded through a turbine to convert heat into mechanical energy. Rankine cycle engines were the most common type of engine used in factories and power plants in the 19th and early 20th centuries. They are still used in some applications today, such as marine propulsion.
* Brayton cycle engines (gas turbines): These engines use a compressor to compress air, which is then mixed with fuel and burned. The hot gases are then expanded through a turbine to convert heat into mechanical energy. Brayton cycle engines are used in jet engines, power plants, and some cars.
Electric Motors
* DC motors: These motors use a direct current (DC) to generate a magnetic field that turns the rotor. DC motors are simple and inexpensive, but they are also less efficient than AC motors. DC motors are used in a variety of applications, including electric vehicles, power tools, and appliances.
* AC motors: These motors use an alternating current (AC) to generate a magnetic field that turns the rotor. AC motors are more efficient than DC motors, but they are also more complex and expensive. AC motors are used in a variety of applications, including appliances, industrial equipment, and power plants.
Hybrid Engines
* Hybrid electric engines: These engines combine an internal combustion engine with an electric motor to improve fuel efficiency. The electric motor can assist the gasoline engine during acceleration, and it can also generate electricity to power the vehicle's electrical systems. Hybrid electric engines are used in a variety of cars and trucks.
* Plug-in hybrid electric engines: These engines combine an internal combustion engine with an electric motor and a larger battery pack. Plug-in hybrid electric vehicles can be plugged in to an external power source to charge the battery, which allows them to travel longer distances on electric power alone. Plug-in hybrid electric vehicles are still relatively new, but they are becoming increasingly popular.
