Two Sedans with more similarities, such as the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy, than differences, like the modifications, horsepower, and fuel economy. First of all, a bigger engine usually means less mpg. But the 2015 Mercedes-Benz CLA-Class CLA 45 AMG has a more powerful engine and it gets 5.5 more mpg than the 2016 Audi S4. Among similarities are the body structure, market segment, starting price, ground shadow size, height, and maximum occupancy.