The fleet of flexible-fuel vehicles in the United States is the second largest in the world after Brazil, and there were more than 21 million 85 flex-fuel vehicles registered in the country by the end of 2017. 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-fuel vehicle. 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.