Two Sedans with more similarities, such as the body structure, starting price, ground shadow size, height, and maximum occupancy, than differences, like the model year, modifications, horsepower, fuel economy, and market segment. First of all, the 2013 Regal GS has a more powerful engine and gets 18 mpg less than the 2016 Sonata Plug-in Hybrid. Among similarities are the body structure, starting price, ground shadow size, height, and maximum occupancy.