The Toyota Prius is a full hybrid electric mid-size hatchback, formerly a compact sedan, manufactured and marketed by Toyota since 1997 and now in its fourth generation. The Prius is widely regarded as the world's first mass-produced hybrid car, and has since become the top-selling hybrid in the world, with over 4 million units sold as of January 2017. The Prius is known for its fuel efficiency and low emissions, and is one of the most fuel-efficient vehicles on the market today.