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Flexible-fuel vehicles in the United States are the second largest flex-fuel fleet in the world after Brazil, and there were about 17.4 million flex-fuel cars and light trucks in operation by the end of 2014. Despite the growing fleet of E85 flex-fuel vehicles, actual use of ethanol fuel is limited due to the lack of E85 refueling infrastructure and also because many American flex-fuel car owners were not aware they owned an E85 flex.〔 Flex-fuel vehicles are common in the Midwest, where corn is a major crop and is the primary feedstock for ethanol fuel production. Also the U.S. government has been using flex-fuel vehicles for many years. U.S. flex-fuel vehicles are optimized to run on a maximum blend of 15% gasoline with 85% anhydrous ethanol (called E85 fuel). This limit in the ethanol content is set to reduce ethanol emissions at low temperatures and to avoid cold starting problems during cold weather, at temperatures lower than . The alcohol content is reduced during the winter in regions where temperatures fall below to a winter blend of E70.〔 ==History== The first commercial flexible fuel vehicle was the Ford Model T, produced from 1908 through 1927. It was fitted with a carburetor with adjustable jetting, allowing use of gasoline or ethanol, or a combination of both. Other car manufactures also provided engines for ethanol fuel use.〔 Oil dominance as a motor fuel was questioned in the U.S. only after the 1973 oil crisis, which resulted in gasoline shortages and awareness on the dangers of oil dependence. This crisis opened a new opportunity for ethanol, methanol and other alternative fuels.〔〔 Also published in the Journal of Scientific & Industrial Research Vol. 62, January–February 2003, pp. 97-105〕 As a response to the shock caused by the first oil crisis, the U.S. government provided the initial support to develop alternative fuels, and some time later, also as a goal to improve air quality. Liquid fuels were preferred over gaseous fuels not only because they have a better volumetric energy density but also because they were the most compatible fuels with existing distribution systems and engines, thus avoiding a big departure from the existing technologies and taking advantage of the vehicle and the refueling infrastructure.〔 California led the search of sustainable alternatives with interest focused in methanol. Ford Motor Company and other automakers responded to California's request for vehicles that run on methanol. In 1981, Ford delivered 40 dedicated methanol fuel (M100) Escorts to Los Angeles County, but only four refueling stations were installed.〔 The biggest challenge in the development of alcohol vehicle technology was getting all of the fuel system materials compatible with the higher chemical reactivity of the fuel. Methanol was even more of a challenge than ethanol but much of the early experience gained with neat ethanol vehicle production in Brazil was transferable to methanol. The success of this small experimental fleet of M100s led California to request more of these vehicles, mainly for government fleets. In 1983, Ford built 582 M100 vehicles; 501 went to California, and the remaining to New Zealand, Sweden, Norway, United Kingdom, and Canada.〔 As an answer to the lack of refueling infrastructure, Ford began development of a flexible-fuel vehicle in 1982, and between 1985 and 1992, 705 experimental FFVs were built and delivered to California and Canada, including the 1.6L Ford Escort, the 3.0L Taurus, and the 5.0L LTD Crown Victoria. These vehicles could operate on either gasoline or methanol with only one fuel system. Legislation was passed to encourage the US auto industry to begin production, which started in 1993 for the M85 FFVs at Ford. In 1996, a new FFV Ford Taurus was developed, with models fully capable of running on either methanol or ethanol blended with gasoline.〔 This ethanol version of the Taurus became the first commercial production of an E85 FFV.〔 Original source: 1996 North American International Auto Show Press Release〕 The momentum of the FFV production programs at the American car companies continued, although by the end of the 1990s, the emphasis shifted to the FFV E85 version, as it is today.〔 Ethanol was preferred over methanol because there is a large support from the farming community, and thanks to the government's incentive programs and corn-based ethanol subsidies. Support for ethanol also comes from the fact that it is a biomass fuel, which addresses climate change concerns and greenhouse gas emissions, though nowadays these benefits are questioned and depend on the feedstock used for ethanol production and their indirect land use change impacts.〔〔 Originally published online in Science Express on 7 February 2008.〕〔 Originally published online in Science Express on 7 February 2008. There are rebuttals to these findings for assuming a worst-case scenario〕 The demand for ethanol fuel produced from field corn in the United States was stimulated by the discovery in the late 90s that methyl tertiary butyl ether (MTBE), an oxygenate additive in gasoline, was contaminating groundwater.〔 Due to the risks of widespread and costly litigation, and because MTBE use in gasoline was banned in almost 20 states by 2006, the substitution of MTBE opened a new market for ethanol fuel.〔 This shift also contributed to a sharp increase in the production and sale of E85 flex vehicles since 2002.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Flexible-fuel vehicles in the United States」の詳細全文を読む スポンサード リンク
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