Convertible

A convertible, also known as a cabriolet, is a passenger car designed to be driven with or without a roof. This unique design allows for an open-air driving experience while providing a roof when weather or conditions require it.

However, removing the roof creates a significant engineering challenge. Without a fixed top, a car loses much of its structural rigidity, which is the stiffness of the vehicle's frame. To prevent the car from flexing or bending, engineers must use specific modifications to counteract the effects of the missing roof structure.

There are three primary types of convertible roofs used in automotive design. The most common is the soft top, which consists of a folding construction framework covered in flexible textile material.

Another option is the retractable hardtop, often called a coupé convertible. This system uses an automatically operated, self-storing hard roof made of metal or plastic.

Finally, there are detachable hardtops. These are rigid, removable roofs that a person must manually take off. These can often be stored in the car's trunk or boot to keep them safe.

Each roof type has different mechanical characteristics and benefits. The soft top uses an articulated folding frame, and the folded mechanism is referred to as the stack.

Some modern designs focus on a low stack height to create a smoother silhouette when the top is down. In contrast, the retractable hardtop offers better security and climate control, though it increases the car's weight and mechanical complexity. While detachable hardtops provide excellent soundproofing and weatherproofing, they are less common today because they cannot be stored inside the vehicle when not in use.

The history of the convertible is tied to the evolution of the automobile itself. Early vehicles were mostly open-air machines without roofs or sides. As engines grew more powerful at the end of the 19th century, folding textile or leather roofs began to appear.

In the 1920s, mass-produced steel bodies made closed cars available to average buyers, causing open cars to fade from the mainstream. By 1939, Plymouth introduced the first mechanically operated convertible roof, which utilized two vacuum cylinders to function.

Following World War II, American soldiers returning from Europe became familiar with small roadster cars, which helped increase demand for these models in the United States.

Convertible sales in the United States reached a peak around 1965. However, popularity began to decline over the next five years due to several factors. The rise of optional air conditioning and the availability of sunroofs or T-tops reduced the appeal of the open body style. Additionally, increased travel speeds on roads led to more wind noise, and new vehicle crash safety standards were introduced. By the mid-1970s, many major American manufacturers had discontinued convertibles. For example, Ford stopped after 1973, and most General Motors divisions stopped after 1975. Cadillac was the last major holdout, producing about 14,000 convertibles in 1976.

Despite the decline in the mid-20th century, the convertible saw a resurgence through new technology and specialized models. In 1989, Mazda released the first-generation MX-5, which became the best-selling convertible with over 1 million units sold.

That same year, Toyota released the Soarer Aerocabin, which utilized an electrically operated retractable hardtop. Specialized companies, known as coachbuilders, also helped by converting regular cars into convertibles. This included the Targa top versions of the AMC Concord and the Toyota Celica "Sunchaser." These efforts helped keep the convertible style alive in the modern market.

Modern convertibles also incorporate advanced technology to improve the driving experience and safety. To manage wind noise, some cars use a windblocker, which can reduce noise by approximately 11 to 12 dB. Some models even feature an "Air Scarf," which is a heating duct directed at the driver's neck.

Safety is also a major focus. Engineers use rollover protection structures, or ROPS, which include roll hoops that deploy during a rollover. They also use boron steel-reinforced A-pillars to create a safety cage. Furthermore, door-mounted side-impact airbags are designed to inflate upward to protect the head, even when the window is open.