Which of the following frame designs are no longer used in automobile manufacturing?

The ladder frame design is indeed less prevalent in modern automobile manufacturing, particularly for passenger vehicles. Historically, the ladder frame was widely used due to its simplicity and strength, consisting of two parallel side rails connected by cross members resembling a ladder. However, advancements in automotive design and safety regulations have shifted the industry towards more modern frameworks.

Manufacturers have favored designs like unibody configurations, which integrate the body and frame into a single structure. This not only reduces weight but also improves fuel efficiency and safety. Additionally, the space frame design offers significant advantages in terms of flexibility and crashworthiness. Tubular frames are often used in specialty applications, such as racing or certain sports cars, due to their lightweight and rigid properties.

While ladder frames can still be found in some trucks and SUVs because of their robustness and ability to handle heavy loads, they are increasingly being replaced by other, more advanced frame designs in most new vehicle models.