Two Convertibles with more similarities, such as the body structure, market segment, starting price, fuel economy, ground shadow size, height, and maximum occupancy, than differences, like the model year and horsepower. First of all, the 2014 Z4 produces fewer horsepower than the 2016 Boxster. Among similarities are the body structure, market segment, starting price, fuel economy, ground shadow size, height, and maximum occupancy.