Flexible-fuel vehicle

thumb|upright=1.09|The [[Ford Model T's engine was capable of running on ethanol, gasoline, kerosene, or a mixture of the first two.]]

A flexible-fuel vehicle (FFV) or dual-fuel vehicle (colloquially called a flex-fuel vehicle) is an alternative fuel vehicle with an internal combustion engine designed to run on more than one fuel, usually gasoline blended with either ethanol or methanol fuel, and both fuels are stored in the same common tank. Modern flex-fuel engines are capable of burning any proportion of the resulting blend in the combustion chamber as fuel injection and spark timing are adjusted automatically according to the actual blend detected by a fuel composition sensor. Flex-fuel vehicles are distinguished from bi-fuel vehicles, where two fuels are stored in separate tanks and the engine runs on one fuel at a time, for example, compressed natural gas (CNG), liquefied petroleum gas (LPG), or hydrogen.

The most common commercially available FFV in the world market is the ethanol flexible-fuel vehicle, These successful tests with P-series fuels were conducted on Ford Taurus and Dodge Caravan flexible-fuel vehicles.

Though technology exists to allow ethanol FFVs to run on any mixture of gasoline and ethanol, from pure gasoline up to 100% ethanol (E100), The alcohol content is reduced during the winter in regions where temperatures fall below to a winter blend of E70 in the U.S. or to E75 in Sweden from November until March. Brazilian flex fuel vehicles are optimized to run on any mix of E20-E25 gasoline and up to 100% hydrous ethanol fuel (E100). The Brazilian flex vehicles were built-in with a small gasoline reservoir for cold starting the engine when temperatures drop below . An improved flex motor generation was launched in 2009 which eliminated the need for the secondary gas tank. In the United States flex-fuel vehicles are also known as "E85 vehicles". In Brazil, the FFVs are popularly known as "total flex" or simply "flex" cars. In Europe, FFVs are also known as "flexifuel" vehicles. Automakers, particularly in Brazil and the European market, use badging in their FFV models with the some variant of the word "flex", such as Volvo Flexifuel, or Volkswagen Total Flex, or Chevrolet FlexPower or Renault Hi-Flex, and Ford sells its Focus model in Europe as Flexifuel and as Flex in Brazil. In the US, only since 2008 FFV models feature a yellow gas cap with the label "E85/Gasoline" written on the top of the cap to differentiate E85s from gasoline only models. Methanol has also been blended with gasoline in flex-fuel vehicles known as M85 FFVs, but their use has been limited mainly to demonstration projects and small government fleets, particularly in California. However, all these vehicles actually are bi-fuel and not flexible-fuel vehicles, because they have engines that store the other fuel in a separate tank, and the engine runs on one fuel at a time. Bi-fuel vehicles have the capability to switch back and forth from gasoline to the other fuel, manually or automatically. The most common available fuel in the market for bi-fuel cars is natural gas (CNG), and by 2008 there were 9.6 million natural gas vehicles, led by Pakistan (2.0 million), Argentina (1.7 million), and Brazil (1.6 million). Natural gas vehicles are a popular choice as taxicabs in the main cities of Argentina and Brazil. Normally, standard gasoline vehicles are retrofitted in specialized shops, which involve installing the gas cylinder in the trunk and the CNG injection system and electronics.

Multifuel vehicles are capable of operating with more than two fuels. In 2004 GM do Brasil introduced the Chevrolet Astra 2.0 with a "MultiPower" engine built on flex fuel technology developed by Bosch of Brazil, and capable of using CNG, ethanol and gasoline (E20-E25 blend) as fuel. This automobile was aimed at the taxicab market and the switch among fuels is done manually. In 2006 Fiat introduced the Fiat Siena Tetra fuel, a four-fuel car developed under Magneti Marelli of Fiat Brazil. This automobile can run as a flex-fuel on 100% ethanol (E100); or on E-20 to E25, Brazil's normal ethanol gasoline blend; Another existing option is to retrofit an ethanol flexible-fuel vehicle to add a natural gas tank and the corresponding injection system. This option is popular among taxicab owners in São Paulo and Rio de Janeiro, Brazil, allowing users to choose among three fuels (E25, E100 and CNG) according to current market prices at the pump. Vehicles with this adaptation are known in Brazil as "tri-fuel" cars.
Flex-fuel hybrid electric and flex-fuel plug-in hybrid are two types of hybrid vehicles built with a combustion engine capable of running on gasoline, E-85, or E-100 to help drive the wheels in conjunction with the electric engine or to recharge the battery pack that powers the electric engine. In 2007 Ford produced 20 demonstration Escape Hybrid E85s for real-world testing in fleets in the U.S. Also as a demonstration project, Ford delivered in 2008 the first flexible-fuel plug-in hybrid SUV to the U.S. Department of Energy (DOE), a Ford Escape Plug-in Hybrid, which runs on gasoline or E85. GM announced that the Chevrolet Volt plug-in hybrid, launched in the U.S. in late 2010, would be the first commercially available flex-fuel plug-in capable of adapting the propulsion to several world markets such as the U.S., Brazil or Sweden, as the combustion engine can be adapted to run on E85, E100 or diesel respectively. The Volt was initially expected to be flex-fuel-capable in 2013, but it was not produced.
In December 2018, Toyota do Brasil announced the development of the world's first commercial hybrid electric car with flex-fuel engine capable of running with electricity and any blend of ethanol fuel and gasoline. The flexible fuel hybrid technology was developed in partnership with several Brazilian federal universities, and a prototype was tested for six months using a Toyota Prius as development mule. Toyota announced plans to start production of a flex hybrid electric car for the Brazilian market in the second half of 2019.

History

The Ford Model T, produced from 1908 through 1927, was fitted with a carburetor with adjustable jetting, allowing use of ethanol, gasoline or kerosene (each by itself), or a combination of the first two mentioned fuels. Other car manufactures also provided engines for ethanol fuel use. It began with a low blend of anhydrous alcohol with regular gasoline in 1976, and since July 2007 the mandatory blend is 25% of alcohol or gasohol E25. after testing with several prototypes developed by Fiat, Volkswagen, GM and Ford. the use of E100-only vehicles sharply declined after increases in sugar prices produced shortages of ethanol fuel.

After extensive research that began in the 90s, a second push took place in March 2003, when the Brazilian subsidiary of Volkswagen launched to the market the first full flexible-fuel car, the Gol 1.6 Total Flex. The adoption of ethanol flex fuel vehicles was so successful, that production of flex cars went from almost 40 thousand in 2003 to 1.7 million in 2007.

In the United States, initial support to develop alternative fuels by the government was also a response to the first oil crisis, and some time later, as a goal to improve air quality. Also, 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. This ethanol version of the Taurus became the first commercial production of an E85 FFV. 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. Sweden also tested both the M85 and the E85 flexifuel vehicles, but due to agriculture policy, in the end emphasis was given to the ethanol flexifuel vehicles. 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.

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. Motorcycles: ABRACICLO 2009, 2011, and 2012. Notes: (1) Includes exports. (2) Total includes gasoline, neat ethanol, flex, and diesel-powered vehicles.

Flexible-fuel technology started being developed by Brazilian engineers near the end of the 1990s. The Brazilian flexible fuel car is built with an ethanol-ready engine and one fuel tank for both fuels. The small gasoline reservoir for starting the engine in cold weather, used in earlier neat ethanol vehicles, was kept to avoid start up problems in the central and southern regions, where winter temperatures normally drop below . Another improvement was the reduction of fuel consumption and tailpipe emissions, between 10% and 15% as compared to flex motors sold in 2008.

thumb|left|Typical Brazilian flexible-fuel engine with secondary gasoline reservoir for cold starting the engine at temperatures below

A key innovation in the Brazilian flex technology was avoiding the need for an additional dedicated sensor to monitor the ethanol-gasoline mix, which made the first American M85 flex fuel vehicles too expensive.

Brazilian flex cars are capable of running on just hydrated ethanol (E100), or just on a blend of gasoline with 25 to 27% anhydrous ethanol (the mandatory blend), or on any arbitrary combination of both fuels.

The flexibility of Brazilian FFVs empowers the consumers to choose the fuel depending on current market prices. As ethanol fuel economy is lower than gasoline because of ethanol's energy content is close to 34% less per unit volume than gasoline, flex cars running on ethanol get a lower mileage than when running on pure gasoline. However, this effect is partially offset by the usually lower price per liter of ethanol fuel. As a rule of thumb, Brazilian consumers are frequently advised by the media to use more alcohol than gasoline in their mix only when ethanol prices are 30% lower or more than gasoline, as ethanol price fluctuates heavily depending on the result of seasonal sugar cane harvests.

thumb|Six typical flex-fuel models from several Brazilian carmakers, popularly known as "flex" cars, that run on any blend of [[hydrous ethanol (E100) and E20-E25 gasoline]]

In March 2003 Volkswagen do Brasil launched in the market the Gol 1.6 Total Flex, the first commercial flexible fuel vehicle capable of running on any blend of gasoline and ethanol. GM do Brasil followed three months later with the Chevrolet Corsa 1.8 Flexpower, using an engine developed by a joint-venture with Fiat called PowerTrain. Passenger flex-fuel vehicles became a commercial success in the country, and , a total of 15 car manufacturers produce flex-fuel engines for the Brazilian market, dominating all light vehicle segments except sports cars, off-road vehicles and minivans. At the end of 2012 registrations of flex-fuel cars and light trucks represented 87% of all passenger and light duty vehicles sold in the country in 2012, and climbed to a 94% market share of all new passenger vehicles sales in 2013. Production passed the 20 million-unit mark in June 2013.

By the end of 2014, flex-fuel cars represented 54% of the Brazilian registered stock of light-duty vehicles, while gasoline only vehicles represented 34.3%. , flex-fuel light-duty vehicle sales totaled 25.5 million units. The market share of flex vehicles reached 88.6% of all light-duty registrations in 2017. , fifteen years after the launch of the first flex fuel car, there were 30.5 million flex cars and light trucks registered in the country, and 6 million flex motorcycles.

The rapid success of flex vehicles was made possible by the existence of 33,000 filling stations with at least one ethanol pump available by 2006, a heritage of the early Pró-Álcool ethanol program. These facts, together with the mandatory use of E25 blend of gasoline throughout the country,

According to two separate research studies conducted in 2009, at the national level 65% of the flex-fuel registered vehicles regularly used ethanol fuel, and the usage climbed to 93% in São Paulo, the main ethanol producer state where local taxes are lower, and prices at the pump are more competitive than gasoline. However, as a result of higher ethanol prices caused by the Brazilian ethanol industry crisis that began in 2009, combined with government subsidies to keep gasoline price lower than the international market value, by November 2013 only 23% flex-fuel car owners were using ethanol, down from 66% in 2009.

thumb|left|The Honda Biz 125 flex is one of the five flex-fuel motorcycles available in Brazil.

One of the latest innovation within the Brazilian flexible-fuel technology is the development of flex-fuel motorcycles. The first flex-fuel motorcycle was launched by Honda in March 2009, the CG 150 Titan Mix. In September 2009, Honda launched a second flexible-fuel motorcycle, the on-off-road NXR 150 Bros Mix. By December 2012 the five available models of flexible-fuel motorcycles from Honda and Yamaha reached a cumulative production of 2,291,072 units, representing 31.8% of all motorcycles manufactured in Brazil since 2009, and 48.2% of motorcycle production in 2012. The 4 million mark was reached in March 2015.

Europe

Sweden

{| class="wikitable" style="float: right; margin-left: 10px"

! colspan="4" style="text-align:center; background:#abcdef;"| Flexi-fuel sales in Sweden Sales by year (2001–2014)

! style="background:#abcdef;"| Year || style="background:#abcdef;"| Sales || style="background:#abcdef;"| Year || style="background:#abcdef;"| Sales

|2001|||| 2008 ||

|2002|| ||2009 ||

|2003|| || 2010 ||

|2004|| || 2011||