Two Convertibles with some similarities, but otherwise different in most aspects such as the modifications, horsepower, fuel economy, ground shadow size, height, starting price, and maximum occupancy. First of all, the 2018 Alfa Romeo 4C Spider is priced $7,600 lower compared to the base MSRP of the 2018 Mercedes-Benz C-Class Convertible AMG C 63. Also, the 2018 C-Class Convertible AMG C 63 has a more powerful engine and gets 9 mpg less than the 2018 4C Spider. In addition, not only 4C Spider is significantly smaller, but it's also shorter than the C-Class Convertible AMG C 63. And then, the Mercedes-Benz C-Class Convertible AMG C 63 seats two more passengers than the Alfa Romeo 4C Spider. Among similarities are the body structure and market segment.