Two Sedans with some similarities, but otherwise different in most aspects such as the model year, starting price, horsepower, and fuel economy. First of all, there is a $19,900 difference in the base MSRP. The 2016 Audi S8, a newer vehicle by three model years, has a higher starting price than the 2013 Mercedes-Benz S-Class. And finally, a bigger engine usually means less mpg. But the 2016 S8 has a more powerful engine and it gets 1 more mpg than the 2013 S-Class. Among similarities are the body structure, market segment, ground shadow size, height, and maximum occupancy.