What is the type of auto body frame that is most often used in today's automobiles?

The unibody frame is the predominant type of auto body structure used in modern automobiles. This design integrates the body and frame into a single entity, which provides enhanced structural rigidity and safety while also reducing weight. The unibody construction allows for more efficient use of materials, resulting in improved fuel economy and better handling characteristics. Additionally, because the frame and body are built together, this design can help to disperse crash forces more effectively in the event of an accident, thereby increasing the safety of the vehicle's occupants.

In contrast, box frames and chassis frames, while still used in some vehicles, are more prevalent in older models or specific types of vehicles like trucks and SUVs due to their durable construction but generally increase the vehicle's weight. Drop frames are less common and primarily feature in specialized vehicles rather than the broader automobile market.