Other hydrocarbon fossil fuels also burnt by deflagration (rather than detonation) in
ICE cars include diesel, autogas, and CNG. Removal of fossil fuel
subsidies,[55][56] concerns about oil dependence, tightening environmental laws and
restrictions on greenhouse gas emissionsare propelling work on alternative power
systems for cars. This includes hybrid vehicles, plug-in electric
vehicles and hydrogen vehicles. As of 2025 one in four cars sold is electric
but,[57] despite rapid growth, less than one in twenty cars on the world's roads
were fully electric and plug-in hybrid cars by the end of 2024.[58] Cars for racing
or speed recordshave sometimes employed jet or rocket engines, but these are
impractical for common use. Oil consumption has increased rapidly in the 20th and
21st centuries because there are more cars; the 1980s oil glut even fuelled the sales
of low-economy vehicles in OECDcountries.[citation needed]
Batteries
Main article: Electric vehicle battery
See also: Electric car § Batteries, and Automotive battery
In almost all hybrid (even mild hybrid) and pure electric cars regenerative
braking recovers and returns to a battery some energy which would otherwise be
wasted by friction brakes getting hot.[59] Although all cars must have friction brakes
(front disc brakes and either disc or drum rear brakes[60]) for emergency stops,
regenerative braking improves efficiency, particularly in city driving.[61]
User interface
Main article: Car controls
In the Ford Model T the left-side hand
lever sets the rear wheel parking brakes and puts the transmission in neutral. The lever to
the right controls the throttle. The lever on the left of the steering column is for ignition
timing. The left foot pedal changes the two forward gears while the centre pedal controls
reverse. The right pedal is the brake.
Cars are equipped with controls used for driving, passenger comfort, and safety,
normally operated by a combination of the use of feet and hands, and occasionally
by voice on 21st-century cars. These controls include a steering wheel, pedals for
operating the brakes and controlling the car's speed (and, in a manual transmission
car, a clutch pedal), a shift lever or stick for changing gears, and a number of buttons
and dials for turning on lights, ventilation, and other functions. Modern cars' controls
are now standardised, such as the location for the accelerator and brake, but this
was not always the case. Controls are evolving in response to new technologies, for
example, the electric car and the integration of mobile communications.
Some of the original controls are no longer required. For example, all cars once had
controls for the choke valve, clutch, ignition timing, and a crank instead of an
electric starter. However, new controls have also been added to vehicles, making
them more complex. These include air conditioning, navigation systems, and in-car
entertainment. Another trend is the replacement of physical knobs and switches by
secondary controls with touchscreen controls such
as BMW's iDrive and Ford's MyFord Touch. Another change is that while early cars'
pedals were physically linked to the brake mechanism and throttle, in the early
2020s, cars have increasingly replaced these physical linkages with electronic
controls.
Electronics and interior
Panel for fuses and circuit breakers
Cars are typically equipped with interior lighting which can be toggled manually or be
set to light up automatically with doors open, an entertainment system which
originated from car radios, sideways windows which can be lowered or raised
electrically (manually on earlier cars), and one or multiple auxiliary power outlets for
supplying portable appliances such as mobile phones, portable fridges, power
inverters, and electrical air pumps from the on-board electrical system.[62][63][a] More
costly upper-class and luxury cars are equipped with features earlier such as
massage seats and collision avoidance systems.[64][65]
Dedicated automotive fuses and circuit breakers prevent damage from electrical
overload.
Lighting
Main article: Automotive lighting
Audi A4 daytime running lights
Cars are typically fitted with multiple types of lights. These include headlights, which
are used to illuminate the way ahead and make the car visible to other users, so that
the vehicle can be used at night; in some jurisdictions, daytime running lights; red
brake lights to indicate when the brakes are applied; amber turn signal lights to
indicate the turn intentions of the driver; white-coloured reverse lights to illuminate
the area behind the car (and indicate that the driver will be or is reversing); and on
some vehicles, additional lights (e.g., side marker lights) to increase the visibility of
the car. Interior lights on the ceiling of the car are usually fitted for the driver and
passengers. Some vehicles also have a boot light and, more rarely, an engine
compartment light.
