Engine displacement in the context of Honda Super Cub

A personal transporter (also powered transporter, electric rideable, personal light electric vehicle, personal mobility device, etc.) is any of a class of compact, mostly recent (21st century), motorised micromobility vehicle for transporting an individual at speeds that do not normally exceed 25 km/h (16 mph). They include electric skateboards, kick scooters, self-balancing unicycles and Segways, as well as gasoline-fueled motorised scooters or skateboards, typically using two-stroke engines of less than 49 cc (3.0 cu in) displacement. Many newer versions use recent advances in vehicle battery and motor-control technologies. They are growing in popularity, and legislators are in the process of determining how these devices should be classified, regulated and accommodated during a period of rapid innovation.

Generally excluded from this legal category are electric bicycles (that are considered to be a type of bicycle); electric motorbikes and scooters (that are treated as a type of motorcycle or moped); and powered mobility aids with 3 or 4 wheels on which the rider sits (which fall within regulations covering powered mobility scooters).

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.

Motorcycling is the act of riding a motorcycle. For some people, motorcycling may be the only affordable form of individual motorized transportation, and small-displacement motorcycles are the most common motor vehicle in the most populous countries, including India, China and Indonesia.

In developing countries, motorcycles are overwhelmingly utilitarian due to lower prices and greater fuel economy. Of all motorcycles, 58% are in the Asia Pacific and Southern and Eastern Asia regions, excluding car-centric Japan.

In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that compresses the intake air, forcing more air into the engine in order to produce more power for a given displacement.

Turbochargers are distinguished from superchargers in that a turbocharger is powered by the kinetic energy of the exhaust gases, whereas a supercharger is mechanically powered, usually by a belt from the engine's crankshaft. However, up until the mid-20th century, a turbocharger was called a "turbosupercharger" and was considered a type of supercharger.

A cubic centimetre (or cubic centimeter in US English) (SI unit symbol: cm; non-SI abbreviations: cc and ccm) is a commonly used unit of volume that corresponds to the volume of a cube that measures 1 cm × 1 cm × 1 cm. One cubic centimetre corresponds to a volume of one millilitre. The mass of one cubic centimetre of water at 3.98 °C (the temperature at which it attains its maximum density) is almost equal to one gram.

In internal combustion engines, "cc" refers to the total volume of its engine displacement in cubic centimetres. The displacement can be calculated using the formula

The Rolls-Royce Merlin is a British liquid-cooled V-12 piston aero engine of 27-litre (1,650 cu in) capacity. Developed as a private venture by Rolls-Royce and first run in 1933, the engine became one of the most successful aircraft engines of World War II, most closely associated with the Hawker Hurricane and Supermarine Spitfire, although the majority of the production run was for the four-engined Avro Lancaster heavy bomber.

Initially known as the PV-12, it was dubbed Merlin after the company convention of naming its four-stroke piston aero engines for birds of prey. The engine benefitted from the racing experiences of precursor engines in the 1930s. After several modifications, the first production variants of the PV-12 were completed in 1936. The first operational aircraft to enter service using the Merlin were the Fairey Battle, Hurricane, and Spitfire. Experience in use led to a series of rapidly applied developments that markedly improved the engine's performance and durability. Starting at 1,000 horsepower (750 kW) for the first production models, most late-war versions produced just under 1,800 horsepower (1,300 kW). The final version, used in the de Havilland Hornet, had over 2,000 horsepower (1,500 kW).

Harley-Davidson, Inc. (H-D, or simply Harley) is an American motorcycle manufacturer and lifestyle brand headquartered in Milwaukee, Wisconsin. Founded in 1903, it is one of two major American motorcycle manufacturers to survive the Great Depression along with its historical rival, Indian Motorcycle Company. The company has survived numerous ownership arrangements, subsidiary arrangements, periods of poor economic health and product quality, and intense global competition to become an iconic brand widely known for its loyal following. There are owner clubs and events worldwide, as well as a company-sponsored, brand-focused museum.

Harley-Davidson is noted for a style of customization that gave rise to the chopper motorcycle style. The company traditionally marketed heavyweight, air-cooled cruiser motorcycles with engine displacements greater than 700 cc, but it has broadened its offerings to include more contemporary VRSC (2002) and middle-weight Street (2014) platforms.

The Ferrari 250 GTO is a grand tourer produced by Ferrari from 1962 to 1964 for homologation into the FIA's Group 3 Grand Touring Car category. It was powered by Ferrari's Tipo 168/62 Colombo V12 engine. The "250" in its name denotes the displacement in cubic centimeters of each of its cylinders; "GTO" stands for Gran Turismo Omologato, Italian for "Grand Touring Homologated".

Just 36 of the 250 GTOs were manufactured between 1962 and 1964. This includes 33 cars with 1962–63 bodywork (Series I) and three with 1964 (Series II) bodywork similar to the Ferrari 250 LM. Four of the older 1962–1963 (Series I) cars were updated in 1964 with Series II bodies.

In the automotive industry, engine downsizing is the practice of utilizing smaller combustion engines over larger ones of the same power capacity when manufacturing vehicles. It is the result of car manufacturers attempting to provide more efficient vehicles that emit fewer emissions, often mandated by legislative standards. The term generally relates to traditional internal combustion engines powered by petrol or diesel.

Many manufacturers are reducing engine displacement and the number of cylinders. By adding a forced aspiration device (turbocharger or supercharger) and direct injection technology, they provide a powerful engine with similar performance to a much larger engine, but with much improved efficiency and reduced carbon emissions. A smaller engine is also often lighter, so less overall energy is expended while driving. Reducing the number of cylinders also reduces the amount of friction in the engine, increasing the efficiency.