Two Convertibles with some similarities, but otherwise different in most aspects such as the starting price, horsepower, fuel economy, ground shadow size, and height. First of all, there is a $58,500 difference in the base MSRP. The 2018 Mercedes-Benz AMG GT Convertible has a higher starting price than the 2018 Alfa Romeo 4C Spider. Also, the 2018 AMG GT Convertible has bigger and thirstier engine; the 2018 4C Spider gets 10.5 more mpg. And finally, not only 4C Spider is significantly smaller, but it's also slightly shorter than the AMG GT Convertible. Among similarities are the body structure, market segment, and maximum occupancy.