4. 2013 Lexus GS 450h
Want a green luxury sedan without owning an Audi? The Lexus GS 450h might appeal to you with its total system output of 338 hp. The Atkinson-cycle V6 hybrid powertrain comes with a 3.5-liter gasoline engine while netting 29 mpg in the city and 34 mpg on the highway. The GS 450h comes at a price however, as the hybrid powertrain commands a premium with a starting price of $61,340.