For space and fuel efficiency, the 2009 Toyota Prius can't be beat. The compact Prius has a design that emphasizes interior space, and thus it qualifies as a mid-size car, which Toyota claims makes it the most fuel-efficient mid-size car in America. The Touring Edition gives the Prius a sportier edge. With front side and side-curtain airbags standard across the line, the Prius is an even better value.