Two Sedans with some similarities, but otherwise different in most aspects such as the fuel economy, ground shadow size, starting price, horsepower, and height. First of all, there is a notable difference in the starting price of the 2015 Audi S3, which is $7,900 less than the base MSRP of the 2016 Kia K900. Also, the 2016 K900 has bigger and thirstier engine; the 2015 S3 gets 7 more mpg. And finally, not only S3 is significantly smaller, but it's also slightly shorter than the K900. Among similarities are the body structure, market segment, and maximum occupancy.