Two Convertibles with more similarities, such as the body structure, market segment, fuel economy, ground shadow size, and maximum occupancy, than differences, like the starting price, horsepower, and height. First of all, there is a $17,500 difference in the base MSRP. The 2018 Alfa Romeo 4C Spider has a higher starting price than the 2018 Mercedes-Benz SLC-Class. Also, the 2018 SLC-Class has a more powerful engine than the 2018 4C Spider. And finally, the 4C Spider is slightly shorter than the SLC-Class. Among similarities are the body structure, market segment, fuel economy, ground shadow size, and maximum occupancy.