Petrol engine in the context of "Ferdinand Porsche"

Gasoline (North American English) or petrol (Commonwealth English) is a petrochemical product characterized as a transparent, yellowish and flammable liquid normally used as a fuel for spark-ignited internal combustion engines. When formulated as a fuel for engines, gasoline is chemically composed of organic compounds derived from the fractional distillation of petroleum and later chemically enhanced with gasoline additives. It is a high-volume profitable product produced in crude oil refineries.

The ability of a particular gasoline blend to resist premature ignition (which causes knocking and reduces efficiency in reciprocating engines) is measured by its octane rating. Tetraethyl lead was once widely used to increase the octane rating but is not used in modern automotive gasoline due to the health hazard. Aviation, off-road motor vehicles, and racing car engines still use leaded gasolines. Other substances are frequently added to gasoline to improve chemical stability and performance characteristics, control corrosion, and provide fuel system cleaning. Gasoline may contain oxygen-containing chemicals such as ethanol, MTBE, or ETBE to improve combustion.

An octane rating, or octane number, is a standard measure of a fuel's ability to withstand compression in an internal combustion engine without causing engine knocking. The higher the octane number, the more compression the fuel can withstand before detonating. Octane rating does not relate directly to the power output or the energy content of the fuel per unit mass or volume, but simply indicates the resistance to detonating under pressure without a spark.

Whether a higher octane fuel improves or impairs an engine's performance depends on the design of the engine. In broad terms, fuels with a higher octane rating are used in higher-compression gasoline engines, which may yield higher power for these engines. The added power in such cases comes from the way the engine is designed to compress the air/fuel mixture, and not directly from the rating of the gasoline.

The diesel engine is an internal combustion engine in which ignition of diesel fuel is caused by the elevated temperature of the air in the cylinder due to mechanical compression; thus, the diesel engine is called a compression-ignition engine (or CI engine). This contrasts with engines using spark plug-ignition of the air-fuel mixture, such as a petrol engine (gasoline engine) or a gas engine (using a gaseous fuel like natural gas or liquefied petroleum gas). The diesel engine is named after its inventor, German engineer Rudolf Diesel.

A diesel–electric transmission, or diesel–electric powertrain, is a transmission system powered by diesel engines for vehicles in road, rail, and marine transport. Diesel–electric transmission is similar to petrol–electric transmission, which is powered by petrol engines.

Diesel–electric transmission is used on railways by diesel–electric locomotives and diesel–electric multiple units, as electric motors are able to supply full torque from 0 RPM. Diesel–electric systems are also used in marine transport, including submarines, and on some other land vehicles.

A hybrid electric vehicle (HEV) is a type of hybrid vehicle that couples a conventional internal combustion engine (ICE) with one or more electric engines into a combined propulsion system. The presence of the electric powertrain, which has inherently better energy conversion efficiency, is intended to achieve either better fuel economy or better acceleration performance than a conventional vehicle. There is a variety of HEV types and the degree to which each functions as an electric vehicle (EV) also varies. The most common form of HEV is hybrid electric passenger cars, although hybrid electric trucks (pickups, tow trucks and tractors), buses, motorboats, and aircraft also exist.

Modern HEVs use energy recovery technologies such as motor–generator units and regenerative braking to recycle the vehicle's kinetic energy to electric energy via an alternator, which is stored in a battery pack or a supercapacitor. Some varieties of HEV use an internal combustion engine to directly drive an electrical generator, which either recharges the vehicle's batteries or directly powers the electric traction motors; this combination is known as a range extender. Many HEVs reduce idle emissions by temporarily shutting down the combustion engine at idle (such as when waiting at the traffic light) and restarting it when needed; this is known as a start-stop system. A hybrid-electric system produces less tailpipe emissions than a comparably sized petrol engine vehicle since the hybrid's petrol engine usually has smaller displacement and thus lower fuel consumption than that of a conventional petrol-powered vehicle. If the engine is not used to drive the car directly, it can be geared to run at maximum efficiency, further improving fuel economy.

A hydrogen internal combustion engine vehicle (HICEV) is a type of hydrogen vehicle using an internal combustion engine that burns hydrogen fuel. Hydrogen internal combustion engine vehicles are different from hydrogen fuel cell vehicles (which utilize hydrogen electrochemically rather than through oxidative combustion). Instead, the hydrogen internal combustion engine is simply a modified version of the traditional gasoline-powered internal combustion engine. The absence of carbon in the fuel means that no CO₂ is produced, which eliminates the main greenhouse gas emission of a conventional petroleum engine.

Pure hydrogen contains no carbon. Therefore, no carbon-based pollutants, such as carbon monoxide (CO), carbon dioxide (CO₂), or hydrocarbons (HC), occur in engine exhaust. However, hydrogen combustion occurs in an atmosphere containing nitrogen and oxygen, which can produce oxides of nitrogen (NO_x). In this respect, the combustion process is much like other high temperature combustion fuels, such as kerosene, gasoline, diesel, and natural gas. Therefore, hydrogen combustion engines are not considered zero emission.