A convertible is an automobile body style with a flexibly operating roof that can convert between open-air or enclosed modes. Roof designs are highly variable from the folding textile roof, known variously as the top, soft top, ragtop or hood — to the folding multi-sectional rigid roof known as a Retractable hardtop, coupé convertible or coupé cabriolet.
Folding textile roofEdit
The collapsible textile roof section (of cloth or vinyl) over an articulated folding frame may include linings such as a sound-deadening layer (e.g.,Volkswagen Beetle) or interior cosmetic headliner (to hide the frame) (e.g.,Chrysler LeBaron) — or both — and may have electrical or electro-hydraulic mechanisms for raising the roof. The erected top secures to the windshield frame header with manual latches (e.g.,Mazda Miata), semi-manual latches, or fully automatic latches (e.g.,Volvo C70). The folded convertible top is called the stack.
Pros and consEdit
Convertibles offer the flexibility of an open top in trade for:
- potentially reduced safety
- poor break-in protection
- deterioration and shrinkage of the sun-exposed textile fabric over time
- diminished rear visibility, from a large roof structure, small rear window, or obstucted rear window — or all of these: e.g.,MINI convertible.
- generally poor structural rigidity. Contemporary engineering goes to great length to counteract the effects of removal of a cars's roof. For example, a 2007 article in the New York Times, referring to the Volkswagen Eos, reported:
- specifically poor structural rigidity, such as pronounced skuttle shake, a characteristic whereby the structural design of the bulkhead between engine and passenger compartment of a convertible suffers sufficiently poor rigidity to negatively impact ride or handling — or allow noticeable vibration, shudder or chassis-flexing into the passenger compartment.
Folding textile convertible tops often do not hide completely the mechanism of the folded top or can expose the vulnerable underside of the folded top to sun exposure and fading — in which case tonneau covers (British: boot) of various designs snap or secure into place to protect the folded roof and hide the mechanicals. Detachable foldable, rigid or semi-rigid covers require space-consuming storage inside the vehicle — and sometimes complicated installation from outside the stationary vehicle. Foldable vinyl and cloth covers can be prone to shrinkage, further complicating installation.
Evolution of the tonneau coverEdit
- The MKI (first generation) MGB (1964) Roadster featured a manually-assembled convertible frame which required the driver to install the separate vinyl or cloth convertible top — from outside the car. Likewise, a similar detachable frame installed to support a foldable vinyl tonneau cover with a series of twenty press fit snaps.
- Convertibles such as the Chrysler LeBaron (c.1988) used sleeve and groove systems to anchor foldable vinyl tonneau cover, again installed manually from outside the car. Later textile convertibles used semi-rigid plastic tonneau covers, e.g., the first generation Audi and Cadillac Allanté.
- Convertibles such as the fifth generation of the Cadillac Eldorado featured a detachable two-part, fully rigid, manually installed tonneau sufficiently strong to support a seated person — also known as a parade boot.
- Convertibles such as the second generation Mercedes SL popularized the integral manually operated self-storing rigid tonneau cover -- in its case accompanied by a separate removable hardtop. In either case, the design required manual operation from outside the stationary vehicle.
- Convertibles such as first Porsche, Toyota MR2 and third generation Mazda Miata featured Z-fold (aka zig-zag fold
Contemporary convertible design may include such features as electrically-heated glass rear window (for improved visibility), seat belt pre-tensioners, boron steel reinforced A-pillers, front and side airbags, safety cage construction — a horseshoe like structure around the passenger compartment — and roll over protection structures or (ROPS) with pyrotechnically charged Roll hoops hidden behind the rear seats that deploy under roll-over conditions whether the roof is retracted or not.
Notably, the Volvo C70 retractable hardtop includes a door-mounted side impact protection inflatable curtain which inflates upward from the interior belt-line — vs. downward like the typical curtain airbag. The curtain has an extra stiff construction with double rows of slats that are slightly offset from each other. This allows them to remain upright and offer effective head protection even an open window. The curtain also deflates slowly to provide protection should the car roll over.
As an example of current convertible safety, the Citroën C3 Pluriel received the following European New Car Assessment Program (Euro NCAP) ratings:
- Adult Occupant: , score 31
- Pedestrian: , score 13
The retractable hardtop solves some issues with the convertible, but has its own comprises, namely mechanical complexity, expense and more often than not, reduced luggage capacity. A 2007 Wall Street Journal article suggested "more and more convertibles are eschewing soft cloth tops in favor of sophisticated folding metal roofs, making them practical in all climates, year-round."
- Retractable hardtop
Convertibles have offered numerous iterations that fall between the first mechanically-simple but attention-demanding fabric tops to the highly complex modern retractable hardtops:
Roadster: Originally the term Roadster suggested a minimal convertible, possibly with a frame that required actual assembly (i.e., not retracting) and separately installable soft "window" panels — offering little protection from inclement weather and requiring a time-consuming, complicated installation. A contemporary roadster is a two-seater convertible.
Landau & Rigid Door: Citroën C3 Pluriel's early Citroën C3 Pluriel featured a roof that rolled back on itself leaving rigidly framed side doors in place — followed in concept by such cars as the 1950 Nash Rambler Convertible Coupe.
Citroën currently markets the Citroën C3 Pluriel (Pluriel is a Cognate with the English plural), which can be configured into five iterations, hence the name:
- a full-length "landau" sedan, operable partially or to the back window or any stage in between, with a buffet-minimizing wind deflector over the windshield. Produced by French coachbuilding specialist Heuliez, the Macarena's top can be folded in 60 seconds, and thereby recalling the Cabriolet (carriage). With its Mazda RX7 convertible, Mazda introduced a two-seater convertible with a removeable rigid section over the passengers, removable independantly of power operated textile section behind with heatable glass rear window. During the 80's, Jaguar produced an XJ-6C with two removable panels over the front seats and a partial fold-down convertible section in the back.
History in the United StatesEdit
Until the 1910 introduction by Cadillac (automobile) of the first closed-body car, the convertible was the primary body style. US automakers manufactured a broad range of models during the 1950s and 1960s — from economical compact-sized models such as the Rambler American and the Studebaker Lark to the more expensive models such as the Packard Caribbean, Oldsmobile 98, and Imperial (automobile) by Chrysler.
Threatened rollover safety regulations in the mid-1970s led to diminished popularity by the 1970s. In 1976 Cadillac marketed the Cadillac Eldorado as "The last convertible in America". During this period of very low convertible production, T-tops became a popular alternatives.
Elsewhere globally, convertible production continued throughout this era with models such as the Mercedes SL, the Volkswagen Beetle, the VW Golf Cabriolet, and the Jaguar.
In the 1980s convertibles such as the Chrysler LeBaron and Saab 900 revived the body style in the United States — followed by models such as the Mazda Miata, Porsche, Audi and later Retractable hardtop models.
- Cabrio coach
- Retractable hardtop
- targa bar
- Carson top
- NASCAR Convertible Division