Under the law, if automakers build flex-fuel cars, they get special permission to make the rest of their cars a little less fuel efficient.

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Also, some Brazilian states (3 of 27) charge a lower VAT (Value Added Tax) on hydrous ethanol sold to Flex-Fuel cars compared to VAT imposed on gasoline at the pump.

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Ethanol output has more than doubled since 2002, thanks to the development of flex-fuel engines for cars, capable of running on either petrol or ethanol indistinguishably.

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On another energy-security front, Woolsey called on automakers to produce fuel-flex cars and for gas stations to offer motorists the choice of gasoline or methanol a liquid fuel made from natural gas to free American transportation from dependence on OPEC.

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Bentley's chief executive Franz-Josef Paefgen, over lunch with journalists in London recently, insisted that "Bentley's engines will be 40% more efficient in four years, and all the cars will be prepared for flex-fuel".

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In Brazil, 90% of new cars sold are so-called flex-fuel vehicles that run on either gas or ethanol.

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Most Brazilian cars can run on a mixture of ethanol and petrol, thanks in part to the flex-fuel engine, developed in the country.

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