What characterizes a unibody vehicle?

A unibody vehicle is characterized by having its body panels welded, bonded, or riveted into a single, rigid structure. This design integrates the body and chassis into one cohesive unit, which enhances the strength and stability of the vehicle. This construction technique not only reduces weight but also improves safety, as the entire structure can better manage and distribute crash forces.

In contrast, the other options describe characteristics of alternative vehicle designs. Loose assembly of separate body panels indicates a construction method where panels are not permanently fastened together, leading to potential structural weakness. Independent components that require separate assembly suggests a body-on-frame design, where the vehicle body and chassis are distinct entities that require individual assembly. Similarly, a body design that uses bolts to hold parts together hints at a more traditional construction method that does not achieve the same level of rigidity as a unibody structure. Thus, the defining feature of a unibody vehicle is its integrated design, which significantly contributes to the vehicle's overall performance and safety.