What exterior feature enhances the sporty design of the QX55?

The fastback silhouette of the QX55 significantly enhances its sporty design by creating a sleek, aerodynamic profile that emphasizes performance and modernity. This design element contributes not only to the vehicle's aesthetic appeal but also to its efficiency and stability at higher speeds, aligning with the sporty characteristics that consumers often seek in a performance-oriented crossover. The flowing lines of a fastback silhouette give the QX55 a dynamic presence on the road, reinforcing its identity as a stylish and athletic vehicle.

Other options, while they may suggest different design focuses, do not encapsulate the sporty essence as effectively as the fastback silhouette. For example, a rugged bumper typically implies a more traditional or off-road capability, and a convertible roof relates more to versatility in design rather than sportiness. Wide wheel arches may suggest a robust appearance but do not specifically highlight the streamlined and agile nature that the fastback silhouette represents. Thus, the fastback shape stands out as the most significant feature contributing to the QX55's sporty aesthetic.