April is being observed as the National Alternative Fuel Autos Month by the auto industry in the United States. In connection with this, the R.L Polk and Co. undertook a study to find out the number of flex fuel vehicles on the country's roads. In Florida, the study found out that the population of alternative fuel vehicles is at 593,000 units last year. That number includes hybrid vehicles, E85 powered vehicles, and those vehicles which are made to be capable of running on biodiesel. The figure shows an improvement of 22.1 percent compared to the number of green vehicles in 2005. Two years ago, the number of alternative fuel vehicles in the state of Florida is estimated to be about 486,000.Dave McCurdy, the President of the Alliance of Automobile Manufacturers, has this to say about the result of the study: "I am proud to see that the sales of Alternative Fuel Autos are rising. The auto industry is a new industry; manufacturers are committed to selling vehicles that can run on something other than just gasoline, and consumers are taking notice." The demand for green cars is the result of the increasing awareness of the threat of global warming amongst American car buyers. Recent spikes in the price of gasoline have forced motorists to look for more fuel efficient vehicles. In Florida, the demand is hugely evidenced by the growing number of alternative fuel vehicles. The state has the third most number of alternative fuel vehicles in the entire land. In the United States, car manufacturers play a major role in the increase of the number of alternative fuel vehicle out in the roads. They have designed and produced alternative fuel vehicles to address the demand of American motorists. In the year 2000, there are only twelve models of alternative fuel vehicles available for the public. After seven years, the number of alternative fuel vehicle models has been multiplied by five so much so that the numbers now equal to a high of sixty. Among the sixty models of alternative fuel vehicles are hybrid electric vehicles, bio-ethanol capable flex fuel vehicles, and biodiesel engined vehicles. The increasing choice of alternative fuel vehicles in the United States played a key role in the huge sales figure of green vehicle last year. In 2006, more than 1.5 million units of alternative fuel vehicles are sold. That number surpassed the Alliance's expected sales.The auto makers' effort to meet the demand for clean vehicles is said to have played a major role in the increased number of alternative fuel vehicles on U.S. roads. According to Walter Dartland, the Executive Director of Consumer Federation of the Southeast, "One of the best ways to address greater fuel efficiency, and less dependence on oil is to drive an alternative fuel automobile. With so many different models currently available, it's clear that auto manufacturers are responding to the wants and needs of today's drivers." These green vehicles offered by car makers are proven to cut down fuel consumption while providing good performance level. These cars' performance can be further enhanced with aftermarket parts such as Vibrant cold air intake systems.