Jump to content

Car

From Wikipedia, the free encyclopedia

This is an old revision of this page, as edited by 151.198.195.2 (talk) at 15:06, 18 December 2007 (Electric). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Karl Benz's "Velo" model (1894) - entered into an early automobile race

An automobile (via French from Greek auto, self and Latin mobilis moving, a vehicle that moves itself rather than being moved by another vehicle or animal) or motor car (usually shortened to just car) is a wheeled passenger vehicle that carries its own motor. Most definitions of the term specify that automobiles are designed to run primarily on roads, to have seating for one to eight people, to typically have four wheels, and to be constructed principally for the transport of people rather than goods.[1] However, the term is far from precise because there are many types of vehicles that do similar tasks.

There were 590 million passenger cars worldwide (roughly one car for every eleven people) as of 2002.[2]

History

File:CarlBenz.jpg
Karl Benz
Replica of the Benz Patent Motorwagen built in 1885

Although Nicolas-Joseph Cugnot is often credited with building the first self-propelled mechanical vehicle or automobile in about 1769, this claim is disputed by some, who doubt Cugnot's three-wheeler ever ran, while others claim Ferdinand Verbiest, a member of a Jesuit mission in China, built the first steam powered car around 1672.[3][4] In either case François Isaac de Rivaz, a Swiss inventor, designed the first internal combustion engine which was fuelled by a mixture of hydrogen and oxygen and used it to develop the world's first vehicle to run on such an engine. The design was not very successful, as was the case with Samuel Brown, Samuel Morey, and Etienne Lenoir who each produced vehicles powered by clumsy internal combustion engines.[5]

In November 1881 French inventor Gustave Trouvé demonstrated a working three-wheeled automobile. This was at the International Exhibition of Electricity in Paris.[6]

An automobile powered by an Otto gasoline engine was built in Mannheim, Germany by Karl Benz in 1885 and granted a patent in January of the following year under the auspices of his major company, Benz & Cie. which was founded in 1883.

Although several other German engineers (including Gottlieb Daimler, Wilhelm Maybach, and Siegfried Marcus) were working on the problem at about the same time, Karl Benz is generally acknowledged as the inventor of the modern automobile.[5] In 1879 Benz was granted a patent for his first engine, designed in 1878. Many of his other inventions made the use of the internal combustion engine feasible for powering a vehicle and in 1896, Benz designed and patented the first internal combustion flat engine.

Approximately 25 Benz vehicles were built and sold before 1893, when his first four-wheeler was introduced. They were powered with four-stroke engines of his own design. Emile Roger of France, already producing Benz engines under license, now added the Benz automobile to his line of products. Because France was more open to the early automobiles, more were built and sold in France through Roger than Benz sold in Germany.

Daimler and Maybach founded Daimler Motoren Gesellschaft (Daimler Motor Company, DMG) in Cannstatt in 1890 and under the brand name, Daimler, sold their first automobile in 1892. By 1895 about 30 vehicles had been built by Daimler and Maybach, either at the Daimler works or in the Hotel Hermann, where they set up shop after falling out with their backers. Benz and Daimler seem to have been unaware of each other's early work and worked independently.

Daimler died in 1900 and later that year, Maybach designed a model named Daimler-Mercedes, special-ordered by Emil Jellinek. Two years later, a new model DMG automobile was produced and named Mercedes after the engine. Maybach quit DMG shortly thereafter and opened a business of his own. Rights to the Daimler brand name were sold to other manufacturers.

Karl Benz proposed co-operation between DMG and Benz & Cie. when economic conditions began to deteriorate in Germany following the First World War, but the directors of DMG refused to consider it initially. Negotiations between the two companies resumed several years later and in 1924 they signed an Agreement of Mutual Interest valid until the year 2000. Both enterprises standardized design, production, purchasing, sales, and advertising—marketing their automobile models jointly—although keeping their respective brands. On June 28, 1926, Benz & Cie. and DMG finally merged as the Daimler-Benz company, baptizing all of its automobiles Mercedes Benz honoring the most important model of the DMG automobiles, the Maybach design later referred to as the 1902 Mercedes-35hp, along with the Benz name. Karl Benz remained a member of the board of directors of Daimler-Benz until his death in 1929.

In 1890, Emile Levassor and Armand Peugeot of France began producing vehicles with Daimler engines, and so laid the foundation of the motor industry in France. The first American car with a gasoline internal combustion engine supposedly was designed in 1877 by George Selden of Rochester, New York, who applied for a patent on an automobile in 1879. In Britain there had been several attempts to build steam cars with varying degrees of success with Thomas Rickett even attempting a production run in 1860.[7] Santler from Malvern is recognized by the Veteran Car Club of Great Britain as having made the first petrol-powered car in the country in 1894[8] followed by Frederick William Lanchester in 1895 but these were both one-offs.[8] The first production vehicles came from the Daimler Motor Company, founded by Harry J. Lawson in 1896, and making their first cars in 1897.[8]

In 1892, German engineer Rudolf Diesel got a patent for a "New Rational Combustion Engine". In 1897 he built the first Diesel Engine.[5] In 1895, Selden was granted a United States patent(U.S. patent 549,160) for a two-stroke automobile engine, which hindered more than encouraged development of autos in the United States. Steam, electric, and gasoline powered autos competed for decades, with gasoline internal combustion engines achieving dominance in the 1910s.

Although various pistonless rotary engine designs have attempted to compete with the conventional piston and crankshaft design, only Mazda's version of the Wankel engine has had more than very limited success.

Ransom E. Olds.

Production

The large-scale, production-line manufacturing of affordable automobiles was debuted by Ransom Olds at his Oldsmobile factory in 1902. This concept was then greatly expanded by Henry Ford, beginning in 1914.

As a result, Ford's cars came off the line in three minute intervals, much faster than previous methods, increasing production by seven to one (requiring 12.5 man-hours before, 1 hour 33 minutes after), while using less manpower.[9] It was so successful, paint became a bottleneck. Only Japan black would dry fast enough, forcing the company to drop the variety of colors available before 1914, until fast-drying Durco lacquer was developed in 1926.[10] In 1914, an assembly line worker could buy a Model T with four months' pay.[11]

Ford's complex safety procedures—especially assigning each worker to a specific location instead of allowing them to roam about—dramatically reduced the rate of injury. The combination of high wages and high efficiency is called "Fordism," and was copied by most major industries. The efficiency gains from the assembly line also coincided with the take off of the United States. The assembly line forced workers to work at a certain pace with very repetitive motions which led to more output per worker while other countries were using less productive methods.

Ford at one point considered suing other car companies because they used the assembly line in their production, but decided against, realizing it was essential to creation and expansion of the industry as a whole.

In the automotive industry, its success was dominating, and quickly spread worldwide. Ford France and Ford Britain in 1911, Ford Denmark 1923, Ford Germany 1925; in 1921, Citroen was the first native European manufactuer to adopt it. Soon, companies had to have assembly lines, or risk going broke; by 1930, 250 companies which did not had disappeared.[12]

Development of automotive technology was rapid, due in part to the hundreds of small manufacturers competing to gain the world's attention. Key developments included electric ignition and the electric self-starter (both by Charles Kettering, for the Cadillac Motor Company in 1910-1911), independent suspension, and four-wheel brakes.

Ford Model T, 1927, regarded as the first affordable automobile

Since the 1920s, nearly all cars have been mass-produced to meet market needs, so marketing plans have often heavily influenced automobile design. It was Alfred P. Sloan who established the idea of different makes of cars produced by one company, so buyers could "move up" as their fortunes improved.

Reflecting the rapid pace of change, makes shared parts with one another so larger production volume resulted in lower costs for each price range. For example, in the 1930s, LaSalles, sold by Cadillac, used cheaper mechanical parts made by Oldsmobile; in the 1950s, Chevrolet shared hood, doors, roof, and windows with Pontiac; by the 1990s, corporate drivetrains and shared platforms (with interchangeable brakes, suspension, and other parts) were common. Even so, only major makers could afford high costs, and even companies with decades of production, such as Apperson, Cole, Dorris, Haynes, or Premier, could not manage: of some two hundred carmakers in existence in 1920, only 43 survived in 1930, and with the Great Depression, by 1940, only 17 of those were left.[13]

In Europe, much the same would happen. Morris set up its production line at Cowley in 1924, and soon outsold Ford, while beginning in 1923 to follow Ford's practise of vertical integration, buying Hotchkiss (engines), Wrigley (gearboxes), and Osberton (radiators), for instance, as well as competitors, such as Wolseley: in 1925, Morris had 41% of total British car production. Most British small-car assemblers, from Autocrat to Meteorite to Seabrook, to name only three, had gone under.[14] Citroen did the same in France, coming to cars in 1919; between them and the cheap cars in reply, Renault's 10CV and Peugeot's 5CV, they produced 550000 cars in 1925, and Mors, Hurtu, and others could not compete.[15] Germany's first mass-manufactured car, the Opel 4PS Laubfrosch (Tree Frog), came off the line at Russelsheim in 1924, soon making Opel the top car builder in Germany, with 37.5% of the market.[16]

Design

The 1955 Citroën DS; revolutionary visual design and technological innovation.

The design of modern cars is typically handled by a large team of designers and engineers from many different disciplines. As part of the product development effort the team of designers will work closely with teams of design engineers responsible for all aspects of the vehicle. These engineering teams include: chassis, body and trim, powertrain, electrical and production. The design team under the leadership of the design director will typically comprise of an exterior designer, an interior designer (usually referred to as stylists), and a color and materials designer. A few other designers will be involved in detail design of both exterior and interior. For example, a designer might be tasked with designing the rear light clusters or the steering wheel. The color and materials designer will work closely with the exterior and interior designers in developing exterior color paints, interior colors, fabrics, leathers, carpet, wood trim, and so on.

In 1924 the American national automobile market began reaching saturation. To maintain unit sales, General Motors instituted annual model-year design changes (also credited to Alfred Sloan) in order to convince car owners they needed a replacement each year. Since 1935 automotive form has been driven more by consumer expectations than engineering improvement.[citation needed]

There have been many efforts to innovate automobile design funded by the NHTSA, including the work of the NavLab group at Carnegie Mellon University.[17]

Acceleration, braking, and measures of turning or agility vary widely between different makes and models of automobile. The automotive publication industry has developed around these performance measures as a way to quantify and qualify the characteristics of a particular vehicle. See quarter mile and 0 to 60 mph.

Fuel and propulsion technologies

Auto rickshaws in New Delhi run on Compressed Natural Gas

Most automobiles in use today are propelled by gasoline (also known as petrol) or diesel internal combustion engines, which are known to cause air pollution and are also blamed for contributing to climate change and global warming.[18] Increasing costs of oil-based fuels and tightening environmental law and restrictions on greenhouse gas emissions are propelling work on alternative power systems for automobiles. Efforts to improve or replace these technologies include hybrid vehicles, electric vehicles and hydrogen vehicles.

Diesel

Diesel engined cars have long been popular in Europe with the first models being introduced in the 1930s by Mercedes Benz and Citroen. The main benefit of Diesels are a 50% fuel burn efficiency compared with 27%[19] in the best gasoline engines. A down side of the diesel is the presence in the exhaust gases of fine soot particulates and manufacturers are now starting to fit filters to remove these. Many diesel powered cars can also run with little or no modifications on 100% biodiesel.

Gasoline

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.[19] Gasoline Direct Injection (GDI) is now starting to appear in production vehicles such as the 2007 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.

Ethanol

Ethanol and other alcohol fuels 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.

klkjngybgn hjbtfyb ngyvwtfysbgyvetygbuygvytgibvgtygbjhgvytinugituybnouygvbyuowwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwweeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee both

Steam

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.[20]

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 several Mazda models. In spite of their impressive smoothness, poor reliability and fuel economy led to them largely disappearing. Mazda, beginning with the 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.

Safety

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.[21]

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,[22] and Henry Bliss, one of the United State's first pedestrian automobile casualties in 1899 in New York.[23]

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.

File: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.[24] There are also tests run by organizations such as IIHS and backed by the insurance industry.[25]

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

The hydrogen powered FCHV (Fuel Cell Hybrid Vehicle) was developed by Toyota in 2005

Cost and benefits of ownership

The costs of automobile ownership, which may include the cost of: acquiring the vehicle, repairs, maintenance, fuel, depreciation, parking fees, tire replacement, taxes and insurance,[26] are weighed against the cost of the alternatives, and the value of the benefits - perceived and real - of vehicle ownership. The benefits may include personal freedom, mobility, independence and convenience.[27]

Cost and benefits to society

Similarly the costs to society of encompassing automobile use, which may include those of: maintaining roads, 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 rapidly from place to place has far reaching implications for the nature of our society. People can now live far from their workplaces, the design of cities can be determined as much by the need to get vehicles into and out of the city as the nature of the buildings and public spaces within the city.[28]

Impacts on society and environment

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.[29] 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.[30] 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.[31] Sprawl is more broadly a factor in inactivity and obesity, which in turn can lead to increased risk of a variety of diseases.[32]

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.[33] In the United States Congress, federally mandated fuel efficiency standards have been debated regularly, passenger car standards have not risen above the 27.5 miles per gallon standard set in 1985. Light truck standards have changed more frequently, and were set at 22.2 miles per gallon in 2007.[34] Alternative fuel vehicles are another option that is less polluting than conventional petroleum powered vehicles.

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[35], 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, and Mobility in mainland Europe.

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.[36] 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.[37] Additional individual modes of transport, such as personal rapid transit could serve as an alternative to automobiles if they prove to be socially accepted.[38]

Further reading

Other automotive topics

References

  1. ^ Pocket Oxford Dictionary. London: Oxford University Press. 1976. ISBN 0-19-861113-7.
  2. ^ "WorldMapper - passenger cars".
  3. ^ "SA MOTORING HISTORY - TIME LINE" (PDF). Government of South Australia.
  4. ^ Setright, L. J. K. (2004). Drive On!: A Social History of the Motor Car. Granta Books. ISBN 1-86207-698-7.
  5. ^ a b c Ralph Stein (1967). The Automobile Book. Paul Hamlyn Ltd.
  6. ^ Wakefield, Ernest H. (1994). History of the Electric Automobile. Society of Automotive Engineers, Inc. p. 2-3. ISBN 1-56091-299-5.
  7. ^ Burgess Wise, D. (1970). Veteran and Vintage Cars. London: Hamlyn. ISBN 0-600-00283-7.
  8. ^ a b c Georgano, N. (2000). Beaulieu Encyclopedia of the Automobile. London: HMSO. ISBN 1-57958-293-1.
  9. ^ Georgano.
  10. ^ Georgano. This is the source of Ford's apocryphal remark, "any color as long as it's black".
  11. ^ Georgano.
  12. ^ Georgano.
  13. ^ Georgano.
  14. ^ Georgano.
  15. ^ Georgano.
  16. ^ Georgano.
  17. ^ "Past projects, NavLab".
  18. ^ "Global Climate Change". U.S. Department of Energy. Retrieved 2007-03-03.
  19. ^ a b Norbye, Jan (1988). Automotive fuel injection Systems. Haynes Publishing. ISBN 0-85429-755-3.
  20. ^ Setright, L.J.K. "Steam: The Romantic Illusion", in Ward, Ian, ed., World of Automobiles (London: Orbis Publishing, 1974), pp.2168-2173.)
  21. ^ "World report on road traffic injury prevention".
  22. ^ "www.universityscience.ie/pages/scientists/sci_mary_ward.php". Retrieved 2007-04-10.
  23. ^ "CityStreets - Bliss plaque".
  24. ^ "SaferCar.gov - NHTSA".
  25. ^ "Insurance Institute for Highway Safety".
  26. ^ "car operating costs". my car. RACV. Retrieved 2006-12-01.
  27. ^ Setright, L. J. K. (2004). Drive On!: A Social History of the Motor Car. Granta Books. ISBN 1-86207-698-7.
  28. ^ John A. Jakle, Keith A. Sculle. (2004). Lots of Parking: Land Use in a Car Culture. ISBN 0813922666.
  29. ^ "Clearing the Air". The Surface Transportation Policy Project. 2003-08-19. Retrieved 2007-04-26. {{cite web}}: Check date values in: |accessdate= and |date= (help)
  30. ^ "Emission Facts". United States Environmental Protection Agency.
  31. ^ "World report on road traffic injury prevention". World Health Organization.
  32. ^ "Our Ailing Communities". Metropolis Magazine.
  33. ^ "Automobiles and the Environment". Greenercars.com.
  34. ^ "CAFE Overview - Frequently Asked Questions". National Highway Traffic Safety Administration.
  35. ^ Paul Werbos. "www.werbos.com/E/WhoKilledElecPJW.htm". Retrieved 2007-04-10. {{cite web}}: Cite has empty unknown parameter: |1= (help)
  36. ^ "Flexcar Expands to Philadelphia". Green Car Congress. 2007-04-02. {{cite web}}: Check date values in: |date= (help)
  37. ^ "About Bike Share Programs". Tech Bikes MIT.
  38. ^ Jane Holtz Kay (1998). Asphalt Nation: how the automobile took over America, and how we can take it back. ISBN 0520216202.

Template:Link FA