Two Convertibles with some similarities, but otherwise different in most aspects such as the model year, ground shadow size, height, starting price, horsepower, and maximum occupancy. First of all, there is a $12,800 difference in the base MSRP. The 2018 Alfa Romeo 4C Spider, an older vehicle by three model years, has a higher starting price than the 2021 BMW 4 Series Convertible. Also, the 2021 4 Series Convertible pulls more horsepower than the 2018 4C Spider. In addition, not only 4C Spider is significantly smaller, but it's also shorter than the 4 Series Convertible. And finally, there is a difference in the number of passengers; the BMW 4 Series Convertible seats two more the Alfa Romeo 4C Spider. Among similarities are the body structure, market segment, and fuel economy.