(EXPANDED FROM 10/27/2021)
Greenhouses have not typically changed as frequently as other parts of the American automobile’s external styling, but they go a long way toward summing up the dominant design approach of a given era.
Before proceeding, we should acknowledge up front that U.S. automakers were much more cautious in exploring innovative approaches to greenhouse design than their European counterparts. For example, none of the postwar American cars matched the Saab 93 or Citroen DS in aerodynamics.
The greenhouse is the part of the car body above the beltline that includes the roof, pillars and glass. The structure of this area is usually so integral to the vehicle that it cannot be changed as easily as front or rear styling. Major changes in a car’s greenhouse have thus mostly occurred when bodies were substantially or completely redesigned.
Fastbacks gave way to notchbacks in the early-50s
Packard offers a good example of the evolution of American car design away from streamlining. The 1948 models were dramatically reskinned from pre-war models but kept the same semi-fastback roofline. Then in 1951 the body was completely redesigned; this included a notchback roofline and substantially more glass area (go here for further discussion).
For 1955 the Packard body was given new front and rear sheetmetal but carried over the roofline except for a new wrap-around windshield (go here).
Even though most car designs of the early-50s shifted to a boxier shape, a few automakers experimented with more streamlined approaches. Most notable was the 1951 Kaiser and the 1953 Studebaker’s low-slung coupes. This design approach may have faded away partly because it was less space efficient.
As the 1950s progressed, greenhouses got lower, longer and wider — much like the rest of American cars. One of the key victims was the hat, which you could no longer wear inside a car because of reduced headroom.
It’s hard to overstate how quickly the basic shape of the American car changed in the 1950s. As a case in point, compare the 1957 Oldsmobile shown at the top of the post with the 1953 Plymouth below. The Plymouth was arguably the last of the “old school” designs that did not sacrifice interior room for stylishness (go here for further discussion).
Curved side glass made greenhouses less boxy
Up through the late-50s side window glass was always flat. The 1957 Imperial was the first mass-produced American car that switched to curved side windows (go here for further discussion). This design trend swept the industry to the point that by 1966 few U.S.-made passenger cars still had flat side glass.
In theory, curved greenhouse sides could increase a car interior’s width by reducing the thickness of doors. That proved to be the case with the 1963-66 Rambler but not the 1961-63 Lincoln Continental. The Rambler was five inches narrower but had the same amount of hip room as the Continental (Consumer Reports, 1963).
Since we are talking about the 1961-63 Continental, it would be worth mentioning that this was the granddaddy of the contemporary four-door coupe (go here for further discussion). In the photograph below, notice how the C-pillar is pushed unusually far forward — which was typical for a two-door hardtop of that era.
Also note that the upper-part of the rear door opening was so small that entry and exit would have been much more challenging if Lincoln had not used forward-opening rear doors.
In the 1960s fastbacks returned — with mixed results
In recent decades fastbacks have have become the dominant greenhouse design for passenger cars. However, in the last half of the 20th Century they were largely relegated to sporty coupes and economy hatchbacks.
Part of the problem was that automakers sometimes struggled to get the proportions right. For example, the 1965-66 Rambler Marlin was the poster child for a vaguely interesting design idea gone terribly wrong.
Two-door models were more rapidly changed
From the 1960s through the 1970s, the greenhouses of two-door body styles tended to receive more frequent redesigns because they were viewed as style leaders.
Perhaps the best example of quickly shifting styling trends was Chevrolet’s full-sized two-door hardtop. Within a 16-year time span General Motors’ designers gave this body style seven different looks.
The 1961 Impala was fairly representative of the dominant look of that time period — a rounded semi-fastback with lots of glass area.
From 1962 to 1964 the Chevrolet — along with its corporate siblings Pontiac, Oldsmobile and Buick — switched to a notchback roof design that was shaped like a convertible. Given that the two-door hardtop body style originally morphed from the convertible, it’s surprising that this approach wasn’t used more often.
For 1965 GM drifted back to a semi-fastback roofline. However, GM’s was more curvaceous than the hardtops offered by Ford, Chrysler and American Motors.
When GM reskinned its full-sized cars for 1967-68, the two-door hardtop curved even more seamlessly into the back deck. That required a different trunk lid than was used on the sedans because it curved upward into the C-pillar (go here for further discussion of the 1968 Chevrolet Impala).
For 1969, swoopy was out and the brougham look was in. All of GM’s full-sized cars received notchback rooflines, often wearing vinyl roofs. Chevrolet had anticipated this trend in 1966, when its top-of-line Caprice two-door hardtop was first given a “brougham-style” notchback roofline not shared with its corporate siblings.
The notchback stuck around through the rest of the 1970s, although in 1975 GM switched from a pillarless design to one that had large B-pillars and “opera windows.”
When GM downsized its big cars in 1977, weight was saved by discontinuing hardtop body styles in favor of pillared sedans. That gave the 1978 Chevrolet Impala pictured below a more utilitarian look. Perhaps GM didn’t care because buyers of two-door models now tended to gravitate toward mid-sized “personal coupes” such as the Monte Carlo, which continued to use frameless door glass.
American greenhouses looked starkly different in 1970s
Passenger cars tended to get lower up until Detroit started to downsize its automotive fleet in the late-70s and early-80s. Height reductions mostly occurred in the greenhouse. That resulted in a turret-topped look to some cars.
A case in point was Chrysler’s 1969-73 full-sized cars, which had a relatively high beltline and a low roofline for two-door hardtops. The 1970 Chrysler New Yorker shown below looks particularly out of proportion (go here for further discussion).
From the 1950s through the 1970s, imported cars provided a strong counterpoint to U.S. automobile design. Emblematic of the time was the Mercedes-Benz W123, which emphasized function over form. That included an unusually tall greenhouse, narrow C-pillars for better rearward-visibility, exposed windshield wipers and thick frames around doors.
Boxy designs of 1980s gave way to aerodynamic shapes
The first half of the 1980s were noteworthy for the extreme boxiness of cars in general and greenhouses in particular. The success of more streamlined designs such as the 1986 Ford Taurus resulted in a gradual shift back to more rounded greenhouses.
By the 2010s even more conservative sedans adopted sharply sloping windshields and semi-fastback rooflines. Typical of this trend was the Infiniti G37 and G50.
Along the way there were some deviations from the norm. For example, The 2004 Chrysler 300C had an unusually boxy greenhouse. This did not help aerodynamics — or styling, for that matter — so its reskinned successor in 2011 reverted to a more sharply raked A-pillar (go here for further discussion).
Less glass area gave greenhouses a less airy look
The 300C is also notable for the squished look of its greenhouse. The intent was presumably to give the car a more sinister look.
Tightening side-impact regulations have also served to reduce the amount of glass area in cars and trucks. As a case in point, the 2018 Ford Expedition looks like it was sat on by the Green Giant. These proportion have become so normalized that one could confuse a 2025 model with that of a Chevrolet Suburban.
As sport-utility vehicles have overtaken regular sedans in popularity, an increasing number of models have shifted to greenhouses with shapes more like sedans or even coupes.
As a case in point, the Ford Mach-E has a decidedly fastback shape while the Hyundai Kona’s rear corners have been rounded off. Meanwhile, the Kia EV6 has adopted more of tall hatchback look.
Does the future belong to ultra-slippery shapes?
In recent years passenger cars have increasingly integrated the hood line with the greenhouse to improve aerodynamics as well as space efficiency.
The 2014-20 Honda Fit illustrates how an unusually sloping front end can match up with a fairly boxy back. In contrast, the 2025 Toyota Prius and Hyundai Ioniq 6 have adopted more teardrop rooflines.
The Ioniq reportedly has a drag coefficient of 0.21, which is among the lowest of production models. The car’s head designer, Simon Loasby said that streamlined cars of the past such as the Stout Scarab and early Saab influenced the Ioniq’s shape.
“The true beginning of aerodynamic design and engineering started in the 1930s and we felt that taking inspiration from that era – and indeed from nature – was the perfect way to create uniqueness and sustainable performance in the EV segment,” Loasby told Dan Mihalascu (2022) of Inside EVs.
It’s ironic that a problem the automobile helped cause — climate change — has pushed automakers to return to the more streamlined greenhouses of the past.
NOTES:
This story that was originally posted on March 1, 2020 and updated on Oct. 27, 2021 and Jan. 28, 2025.
RE:SOURCES
- Consumer Reports; 1963. “Basic Body Dimensions.” Published April; p. 165.
- Mihalascu, Dan; 2022. “Hyundai Reveals Secrets Behind Ioniq 6’s Top Aerodynamic Efficiency.” Inside EVs. Posted Nov. 10.
ADVERTISING & BROCHURES:
- oldcaradvertising.com: Chevrolet (1961, 1963, 1978)
- oldcarbrochures.org: Chevrolet (1965, 1968, 1976, 1978); Chrysler (1970)
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