The car analogy is a common resort exploited by engineering

Engineering

Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...

 textbooks to ease the understanding of some abstract concepts found within it.

Uses of car analogies

The efficiency of car analogies reside on their capacity to explain hard concepts (usually due to their high abstraction level) on more mundane terms with which the target audience is comfortable, and with which many also have a special interest. Due to that, car analogies appear more often on works related to applied sciences and technology

Technology

Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...

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In order to work, car analogies translate agent

Agent (grammar)

In linguistics, a grammatical agent is the cause or initiator of an event. Agent is the name of the thematic role...

s of action as the car driver, the seller, or police officers; likewise, elements of a system

System

System is a set of interacting or interdependent components forming an integrated whole....

 are referred as car pieces, such as wheel

Wheel

A wheel is a device that allows heavy objects to be moved easily through rotating on an axle through its center, facilitating movement or transportation while supporting a load, or performing labor in machines. Common examples found in transport applications. A wheel, together with an axle,...

s, motor, or ignition keys. Resources tend to appear as gas

Gas

Gas is one of the three classical states of matter . Near absolute zero, a substance exists as a solid. As heat is added to this substance it melts into a liquid at its melting point , boils into a gas at its boiling point, and if heated high enough would enter a plasma state in which the electrons...

, speed, or as the money that can be spent on better accessories/vehicles.

For example, in the paragraph:

"Zener diodes regulate voltage by acting as complementary loads, drawing more or less current as necessary to ensure a constant voltage drop across the load. This is analogous to regulating the speed of an automobile by braking rather than by varying the throttle position."

current (resource) is depicted as the car's speed, while the role of the brakes is performed by the Zener diodes (element of the system).

Car analogies are also typically used to explain the quality differences between two similar tools or hardware

Hardware

Hardware is a general term for equipment such as keys, locks, hinges, latches, handles, wire, chains, plumbing supplies, tools, utensils, cutlery and machine parts. Household hardware is typically sold in hardware stores....

 pieces; in that case, the best one is usually described as a Ferrari

Ferrari

Ferrari S.p.A. is an Italian sports car manufacturer based in Maranello, Italy. Founded by Enzo Ferrari in 1929, as Scuderia Ferrari, the company sponsored drivers and manufactured race cars before moving into production of street-legal vehicles as Ferrari S.p.A. in 1947...

 or a Rolls Royce

Rolls-Royce (car)

This a list of Rolls-Royce motor cars and includes vehicles produced by:*Rolls-Royce Limited *Rolls-Royce Motors , which was owned by Vickers between 1980 and 1998, and after that by Volkswagen...

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