Editing Automobile accessory power (section)

{{Short description|Power in cars}}
{{More citations needed|date=June 2021}}
[[Image:Energy flows in car.svg|thumb|right|450px|Example energy flows for a late-model midsize passenger car: (a) urban driving; (b) highway driving. Source: U.S. Department of Energy [http://www.fueleconomy.gov/feg/atv.shtml/]]]
'''Automobile accessory power''' can be transferred by several different means.  However, it is always ultimately derived from the [[automobile]]'s [[engine|internal combustion engine]], battery, or other "prime mover" source of energy.  The advent of high-powered batteries in hybrid and all-electrical vehicles is shifting the balance of technologies even further in the direction of electrically powered accessories.

An engine has one or more devices for converting energy it produces into a usable form, [[electrical|electricity]] connection through the alternator, [[hydraulic]] connections from a pump or engine system,  [[Pneumatics|compressed air]], and engine [[vacuum]]; or the engine may be directly tapped through a [[Machine|mechanical]] connection. Modern vehicles run most accessories on electrical power. Typically, only 2% of a vehicle's total power output has gone towards powering accessories.<ref name=autogenerated2>[http://www.trb.org/publications/sr/sr286.pdf TRANSPORTATION RESEARCH BOARD SPECIAL REPORT 286 TIRES AND PASSENGER VEHICLE FUEL ECONOMY Fig 3-1, p.63 of pdf, p.40 of report]</ref> Electrical and hybrid vehicles may use a larger proportion of energy for accessories, due to reduced inefficiencies in the drive train, especially the elimination of engine idling.