As I understand it, the gas crisis of the mid 70’s saw everyone shifting from making/buying cars that were either as big or as powerful as possible and getting sometimes single digit gas mileage to much more fuel efficient vehicles. But while cars got smaller and lighter and engines got handicapped for the sake of efficiency, it seemed that cars of this period were some of the least aerodynamic vehicles since the dawn of automobiles, especially compared to the bubble cars of the 40s and 50s. This seems counter productive.
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Aerodynamics for cars were not well understood until the late 70’s and 80’s and car manufacturers didn’t really think about it that much. Making cars lighter and limiting engines was a lot easier and auto manufacturers mostly didn’t have things like wind tunnels.
So car manufacturers did make aero friendly cars, but they were mostly intended for racing. The average street car was a brick. Earlier cars from the 50’s and 60’s look far more aerodynamic than they actually were. The rounded surfaces often were structural rather than aerodynamic, it wasn’t about moving the air around the car so much as the support it’s weight and shape.
Body panels in this era were all made by hand, but by the 70’s machine made parts and unibody cars started to appear which caused them to take on a squarer shape.
Even in the top echelons of motorsport like Formula 1 they didn’t really understand or use aero until in the mid 70’s.
They knew from aircraft that thin and narrow cars sliced through the air better, but cars built to channel air around them to make downforce didn’t really appear until the mid 70’s.
If you consider that the auto industry is often 10 years behind racing, then car manufacturers didn’t really start thinking about aero until the mid 80’s.
Even the famous Lamborghini Countach looks sleek and aerodynamic but it’s actually a pig. Stick it in the windtunnel and it’s awful. The spoiler does nothing and the car generates lift instead of downforce. So just because a car *looks* aerodynamic doesn’t mean that it is!
Looking back, it’s funny to see how the 80’s in reality was just as blocky as the 80’s computer graphics. It was also the time when computers starting taking over manufacturing designs, and their 8 bit resolution manifested in the items it produced.
Here is a bunch of videos about that period, known as malaise era: https://youtu.be/hnMh5rTe-KY
It’s a deep and fun dive into the question
My 86 Corolla had a very low coefficient of drag but was all angles. You can’t tell by looking if something is aerodynamic or not. Just look at a new Prius. Brought to you by WTF designs.
1935 Tatra T77a was .212
VW beetle was .48
84 Audi 5000s was .36
08 Tesla Roadster was .35
86 Corolla cd was .34
86 Taurus was .32
95 Mazda Mellenia was .29
92 Subaru SVX was .29
21 Prius is .24
So not all that much progress.
Until 1940 to 1958 there was only one legal headlight assembly in America, single 7″ round sealed headlights. In 1959 they allowed dual 7″ round headlights per side (vertical or horizontal were fine).
In 1975 they legalized square headlights that are so iconic of 1980’s vehicles. It wasn’t until 1984 that they legalized unsealed headlight assemblies with replaceable bulbs molded in a variety of shapes that could flow with the rest of the shape of the car.
When you’re only allowed one headlight assembly with a vertical face pasted to the front of the vehicle, it’s going to limit the amount of reasonable looking vehicle designs. Before composite headlight assemblies, the only way to make a reasonably good looking car with sealed beams starts with a flat, vertical nose.
As an example of a car that experienced an aerodynamic improvement late in its life (1991->1992, one of the last boxes), Ford Crown Victoria went from a drag coefficient ^[1] 0.42 to 0.34, when moving from the earlier boxy styling to something much more modern.
While this change would make a considerable impact on efficiency at modern highway/tollway speeds (often 75MPH and higher), it would not make anywhere near the same impact if the 55MPH “National Minimum Speed Limit” ^[2] were rigorously enforced, as drag rises exponentially ^[3] with speed.
I suppose, though cannot confirm, that the lack of improvement may have been partially driven by this lack of apparent need.
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^1 [^Drag ^coefficient](https://en.wikipedia.org/wiki/Drag_coefficient) ^- ^basically ^how ^draggy ^something ^is, ^without ^considering ^its ^area ^or ^total ^drag
^2 ^[NMSL](https://en.wikipedia.org/wiki/National_Maximum_Speed_Law) ^law ^enacted ^in ^1973, ^changed ^to ^65MPH ^in ^1987, ^repealed ^1995
^3 ^This ^is ^an ^oversimplification; ^as ^another ^user ^pointed ^out, ^this ^is ^more ^or ^less ^true ^at ^higher ^speeds, ^but ^gets ^more ^complicated ^as ^one ^moves ^slower.
One reason is the NHTSA refused to allow plastic headlights until the mid 1980’s, many years after they started using them in Europe
So in the 1970’s and 1980’s, there were several things at play. Fuel economy was a concern. The EPA mandated catalytic converters for all 1975 production gasoline vehicles in addition to other Clean Air act requirements which severely limited the overall efficiency of the engines (not to mention you had manufacturers like Ford reclassifying the F100 half ton pickup as a heavy half ton F150 to circumvent some of those requirements for a few years). In addition, the American Society of Automotive Engineers (SAE) came in and standardized how engines were tested for power output. So within a couple of years you had American muscle that went from being rated to 300 hp, 350 hp and even 400 hp to not even breaking the 200 hp mark.
In the 80’s manufacturers began introducing fuel injection (granted throttle body fuel injection is just glorified carburetion), transmissions with overdrive gearing, etc but gas was cheap again and would stay that way until a pretty major event in 2001. However, the Japanese imports won the economy war as they were building reliable, simple and efficient vehicles. Detroit is still catching up…granted I love my GM small blocks but when it comes to domestics, you can have reliable, well built, and efficient but you can only pick two.
Terrible answers.
There are two main forms of drag particularly when it comes to things like a car.
1. Air resistance that is caused by the cross sectional area of an object that is being exposed to airflow.
2. Skin friction that is caused by the shape itself (i.e. a square vs a circle).
The first option is significantly more impactful than the second hence why cars from the era, and even into the 90s and 2000s tend to be significantly smaller than cars now or in the 50s and 60s.
**The explanation only gets longer from here.**
Option 2 is also significantly more difficult to manufacture. Steel likes being bent in simple shapes. Making complex aerodynamic shapes is really rather difficult, compared to say making a box with rounded corners.
Simply rounding off the corners of a square goes a long way to reducing flow separation and is significantly more easy to manufacture. It’s the operating principle behind the truck tails.
***Why is it more difficult to manufacture aerodynamic shapes?***
Because when you bend metal you aren’t moving the material into a perfect bend, you are stretching the outside of the bend, while compressing the inside of the bend which leaves a surface that is either measurably, or visibly, warped in the location of the bend.
Other commenters have suggested that early CAD programs made it more difficult to have complex shapes. Maybe that did play some sort of role, but I’ve dealt with complex casting drawings in my career that were drawn in the 50s, 60s, 70s, and 80s that were done by hand that are just as complex as drawings I make now.
***Why make body panels out of metal then, why not something like plastic that can be molded to any shape?***
Well it’s been tried plenty of times before and it is definitely a workable solution, at least from the engineering sense.
However, from the aesthetic design perspective, plastic, or other non-ferrous materials have been problematic because they don’t expand and contract at the same rate as the steel that inevitably makes up the frames of cars.
Also depending on the era, plastics might have had poor structural properties, and even worse UV resistance.
The 1980’s also gave us the Honda CRX that would get 68MPG:
https://www.hemmings.com/stories/2013/06/24/lost-cars-of-the-1980s-honda-civic-crx
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