Gasoline

Main article: Petrol engine

2007 Mark II (BMW) Mini Cooper
2007 Mark II (BMW) Mini Cooper

Gasoline engines have the advantage over diesel in being lighter and able to work at higher rotational speeds and they are the usual choice for fitting in high-performance sports cars. Continuous development of gasoline engines for over a hundred years has produced improvements in efficiency and reduced pollution. The carburetor was used on nearly all road car engines until the 1980s but it was long realised better control of the fuel/air mixture could be achieved with fuel injection. Indirect fuel injection was first used in aircraft engines from 1909, in racing car engines from the 1930s, and road cars from the late 1950s.[18] Gasoline Direct Injection (GDI) is now starting to appear in production vehicles such as the 2007 (Mark II) BMW Mini. Exhaust gases are also cleaned up by fitting a catalytic converter into the exhaust system. Clean air legislation in many of the car industries most important markets has made both catalysts and fuel injection virtually universal fittings. Most modern gasoline engines are also capable of running with up to 15% ethanol mixed into the gasoline - older vehicles may have seals and hoses that can be harmed by ethanol. With a small amount of redesign, gasoline-powered vehicles can run on ethanol concentrations as high as 85%. 100% ethanol is used in some parts of the world (such as Brazil), but vehicles must be started on pure gasoline and switched over to ethanol once the engine is running. Most gasoline engined cars can also run on LPG with the addition of an LPG tank for fuel storage and carburetion modifications to add an LPG mixer. LPG produces fewer toxic emissions and is a popular fuel for fork lift trucks that have to operate inside buildings.
The hydrogen powered FCHV (Fuel Cell Hybrid Vehicle) was developed by Toyota in 2005
The hydrogen powered FCHV (Fuel Cell Hybrid Vehicle) was developed by Toyota in 2005

Bioalcohols and biogasoline

Ethanol, other alcohol fuels (biobutanol) and biogasoline have widespread use an automotive fuel. Most alcohols have less energy per liter than gasoline and are usually blended with gasoline. Alcohols are used for a variety of reasons - to increase octane, to improve emissions, and as an alternative to petroleum based fuel, since they can be made from agricultural crops. Brazil's ethanol program provides about 20% of the nations automotive fuel needs, including several million cars that operate on pure ethanol.

Electric

Main articles: Battery electric vehicle, Hybrid vehicle, and Plug-in hybrid

The Henney Kilowatt, the first modern (transistor-controlled) electric car.
The Henney Kilowatt, the first modern (transistor-controlled) electric car.
2007 Tesla electric powered Roadster
2007 Tesla electric powered Roadster

The first electric cars were built around 1832, well before internal combustion powered cars appeared.[19] For a period of time electrics were considered superior due to the silent nature of electric motors compared to the very loud noise of the gasoline engine. This advantage was removed with Hiram Percy Maxim's invention of the muffler in 1897. Thereafter internal combustion powered cars had two critical advantages: 1) long range and 2) high specific energy (far lower weight of petrol fuel versus weight of batteries). The building of battery electric vehicles that could rival internal combustion models had to wait for the introduction of modern semiconductor controls and improved batteries. Because they can deliver a high torque at low revolutions electric cars do not require such a complex drive train and transmission as internal combustion powered cars. Some post-2000 electric car designs such as the Venturi Fétish are able to accelerate from 0-60 mph (96 km/h) in 4.0 seconds with a top speed around 130 mph (210 km/h). Others have a range of 250 miles (400 km) on the EPA highway cycle requiring 3-1/2 hours to completely charge[20]. Equivalent fuel efficiency to internal combustion is not well defined but some press reports give it at around 135 mpg–U.S. (1.74 L/100 km / 162.1 mpg–imp).

Steam

Main article: steam car

Steam power, usually using an oil or gas heated boiler, was also in use until the 1930s but had the major disadvantage of being unable to power the car until boiler pressure was available. It has the advantage of being able to produce very low emissions as the combustion process can be carefully controlled. Its disadvantages include poor heat efficiency and extensive requirements for electric auxiliaries.[21]

Gas turbine

In the 1950s there was a brief interest in using gas turbine (jet) engines and several makers including Rover and Chrysler produced prototypes. In spite of the power units being very compact, high fuel consumption, severe delay in throttle response, and lack of engine braking meant no cars reached production.

Rotary (Wankel) engines

Rotary Wankel engines were introduced into road cars by NSU with the Ro 80 and later were seen in the Citroën GS Birotor and several Mazda models. In spite of their impressive smoothness, poor reliability and fuel economy led to them largely disappearing. Mazda, beginning with the R100 then RX-2, has continued research on these engines, overcoming most of the earlier problems with the RX-7 and RX-8.

Rocket and jet cars

A rocket car holds the record in drag racing. However, the fastest of those cars are used to set the Land Speed Record, and are propelled by propulsive jets emitted from rocket, turbojet, or more recently and most successfully turbofan engines. The ThrustSSC car using two Rolls-Royce Spey turbofans with reheat was able to exceed the speed of sound at ground level in 1997.

Safety

Main articles: Car safety and Automobile accident

Result of a serious automobile accident.
Result of a serious automobile accident.

Road traffic injuries represent about 25% of worldwide injury-related deaths (the leading cause) with an estimated 1.2 million deaths (2004) each year.[22]

Automobile accidents are almost as old as automobiles themselves. Early examples include Mary Ward, who became one of the first documented automobile fatalities in 1869 in Parsonstown, Ireland,[23] and Henry Bliss, one of the United State's first pedestrian automobile casualties in 1899 in New York.[24]

Cars have many basic safety problems - for example, they have human drivers who can make mistakes, wheels that can lose traction when braking, turning or acceleration forces are too high, and mechanical systems subject to failure. Collisions can have very serious or fatal consequences. Some vehicles have a high center of gravity and therefore an increased tendency to roll over.

Early safety research focused on increasing the reliability of brakes and reducing the flammability of fuel systems. For example, modern engine compartments are open at the bottom so that fuel vapors, which are heavier than air, vent to the open air. Brakes are hydraulic and dual circuit so that a total braking failure is very rare. Systematic research on crash safety started[citation needed] in 1958 at Ford Motor Company. Since then, most research has focused on absorbing external crash energy with crushable panels and reducing the motion of human bodies in the passenger compartment. This is reflected in most cars produced today.
Image:Airbag system.jpg
Airbags, a modern component of automobile safety

Significant reductions in death and injury have come from the addition of Safety belts and laws in many countries to require vehicle occupants to wear them. Airbags and specialised child restraint systems have improved on that. Structural changes such as side-impact protection bars in the doors and side panels of the car mitigate the effect of impacts to the side of the vehicle. Many cars now include radar or sonar detectors mounted to the rear of the car to warn the driver if he or she is about to reverse into an obstacle or a pedestrian. Some vehicle manufacturers are producing cars with devices that also measure the proximity to obstacles and other vehicles in front of the car and are using these to apply the brakes when a collision is inevitable. There have also been limited efforts to use heads up displays and thermal imaging technologies similar to those used in military aircraft to provide the driver with a better view of the road at night.

There are standard tests for safety in new automobiles, like the EuroNCAP and the US NCAP tests.[25] There are also tests run by organizations such as IIHS and backed by the insurance industry.[26]

Despite technological advances, there is still significant loss of life from car accidents: About 40,000 people die every year in the United States, with similar figures in European nations. This figure increases annually in step with rising population and increasing travel if no measures are taken, but the rate per capita and per mile traveled decreases steadily. The death toll is expected to nearly double worldwide by 2020. A much higher number of accidents result in injury or permanent disability. The highest accident figures are reported in China and India. The European Union has a rigid program to cut the death toll in half by 2010, and member states have started implementing measures.

Automated control has been seriously proposed and successfully prototyped. Shoulder-belted passengers could tolerate a 32 g emergency stop (reducing the safe inter-vehicle gap 64-fold) if high-speed roads incorporated a steel rail for emergency braking. Both safety modifications of the roadway are thought to be too expensive by most funding authorities, although these modifications could dramatically increase the number of vehicles able to safely use a high-speed highway. This makes clear the often-ignored fact road design and traffic control also play a part in car wrecks; unclear traffic signs, inadequate signal light placing, and poor planning (curved bridge approaches which become icy in winter, for example), also contribute.

Economics and impacts
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Cost and benefits of usage

Main article: Economics of automobile usage

The costs of automobile usage, which may include the cost of: acquiring the vehicle, repairs, maintenance, fuel, depreciation, parking fees, tire replacement, taxes and insurance,[27] are weighed against the cost of the alternatives, and the value of the benefits - perceived and real - of vehicle usage. The benefits may include on-demand transportation, mobility, independence and convenience.[28]

Cost and benefits to society

Main article: Effects of the automobile on societies

Similarly the costs to society of encompassing automobile use, which may include those of: maintaining roads, land use, pollution, public health, health care, and of disposing of the vehicle at the end of its life, can be balanced against the value of the benefits to society that automobile use generates. The societal benefits may include: economy benefits, such as job and wealth creation, of automobile production and maintenance, transportation provision, society wellbeing derived from leisure and travel opportunities, and revenue generation from the tax opportunities. The ability for humans to move flexibly from place to place has far reaching implications for the nature of societies. [29]

Impacts on society and environment
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Further information: Global warming

Transportation is a major contributor to air pollution in most industrialised nations. According to the American Surface Transportation Policy Project nearly half of all Americans are breathing unhealthy air. Their study showed air quality in dozens of metropolitan areas has got worse over the last decade.[30] In the United States the average passenger car emits 11,450 lbs (5 tonnes) of carbon dioxide, along with smaller amounts of carbon monoxide, hydrocarbons, and nitrogen.[31] Residents of low-density, residential-only sprawling communities are also more likely to die in car collisions, which kill 1.2 million people worldwide each year, and injure about forty times this number.[32] Sprawl is more broadly a factor in inactivity and obesity, which in turn can lead to increased risk of a variety of diseases.[33]

Improving the positive and reducing the negative impacts

Fuel taxes may act as an incentive for the production of more efficient, hence less polluting, car designs (e.g. hybrid vehicles) and the development of alternative fuels. High fuel taxes may provide a strong incentive for consumers to purchase lighter, smaller, more fuel-efficient cars, or to not drive. On average, today's automobiles are about 75 percent recyclable, and using recycled steel helps reduce energy use and pollution.[34] In the United States Congress, federally mandated fuel efficiency standards have been debated regularly, passenger car standards have not risen above the 27.5 mpg–U.S. (8.55 L/100 km / 33 mpg–imp) standard set in 1985. Light truck standards have changed more frequently, and were set at 22.2 mpg–U.S. (10.6 L/100 km / 26.7 mpg–imp) in 2007.[35] Alternative fuel vehicles are another option that is less polluting than conventional petroleum powered vehicles.

Future car technologies

Main article: Future car technologies

Automobile propulsion technology under development include gasoline/electric and plug-in hybrids, battery electric vehicles, hydrogen cars, biofuels, and various alternative fuels.

Research into future alternative forms of power include the development of fuel cells, Homogeneous Charge Compression Ignition (HCCI), stirling engines[36], and even using the stored energy of compressed air or liquid nitrogen.

New materials which may replace steel car bodies include duraluminum, fiberglass, carbon fiber, and carbon nanotubes.

Telematics technology is allowing more and more people to share cars, on a pay-as-you-go basis, through such schemes as City Car Club in the UK, Mobility in mainland Europe, and Zipcar in the US.

Alternatives to the automobile

Main article: Alternatives to the automobile

Established alternatives for some aspects of automobile use include public transit (buses, trolleybuses, trains, subways, monorails, tramways), cycling, walking, rollerblading and skateboarding. Car-share arrangements are also increasingly popular–the U.S. market leader has experienced double-digit growth in revenue and membership growth between 2006 and 2007, offering a service that enables urban residents to "share" a vehicle rather than own a car in already congested neighborhoods.[37] Bike-share systems have been tried in some European cities, including Copenhagen and Amsterdam. Similar programs have been experimented with in a number of U.S. Cities.[38] Additional individual modes of transport, such as personal rapid transit could serve as an alternative to automobiles if they prove to be socially accepted