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On the many possible causes for the death of the American convertible in the Seventies

Published in blog.hemmings.com

1976 Cadillac Eldorado convertible. Image courtesy OldCarBrochures.org.

The American convertible, as we all know, died after Cadillac churned out 14,000 Eldorados in 1976 and wealthy speculators latched on to them as some of the first “instant collectible” cars. And then less than a decade later, it was back. The standard explanation for the convertible’s disappearance has seemingly always been something about federal safety standards, but is that really the case?

Though the article’s a few months old, one of Litwin’s This or That pieces from April — pitting a Buick Electra 225 convertible against a Chrysler 300 convertible — generated a new thread of discussion this week about the factors behind the convertible’s demise. The thread started with a comment from Ken S.:

As the owner of a ’69 Mustang convertible, I am acutely aware of the plunge in convertible production that occurred from 1968 on. Of the quarter of a million first-generation Mustang convertibles built, almost all were 1965-1967 vehicles. By 1969, the annual production was down to 14,746 and barely over 7,000 in 1970. What happened to the convertible concept that caused sales to fall so precipitously in the late 60s? Did it have anything to do with federal regulation?

Indeed, we looked through production numbers for the 1965 through 1973 Mustangs and noticed a steady downward trend for convertibles as a share of overall model production through 1970 (from 22.8 percent to 3.9 percent), then a slow recovery through 1973 (back up to 8.8 percent). Perhaps the steepest decline came between 1968 and 1969, when convertibles dropped from 8 percent to 4.9 percent of overall Mustang production.

Because we had our reference books out, we also took a look at other convertibles that could be considered bellwethers for that market at that time. Thunderbird convertibles steadily made up at least an eighth of total Thunderbird production from 1960 to 1962 before making their own slow decline to 7.3 percent in 1966, the last year for the Thunderbird convertible (in period). And while convertible Corvettes enjoyed as much as a 65-percent share of production from 1964 to 1968, those numbers quickly spiraled downward from 1969 on, plummeting to 12 percent in 1975.

Were we to take the time to chart out all convertible numbers during this time period, we’d probably see similar trends — noteworthy declines after 1968, but no universal cliff over which the numbers of convertibles plummeted, suggesting causes other than something hard and drastic like rollover standards. Rather, we see gentle slopes downward starting early in the Sixties.

So what happened? Fortunately, Ken S.’ comment drew some replies. First, from Steven Visek:

People often cite federal rollover regulations as causing the decline in convertibles. This is misguided. First, as you have said, the decline began in the 1960s. The related proposed (but not actually adopted) government rollover standards that are cited were not even proposed until January of 1971.

While the spectre of such regulations may very well have played a role in subsequent decisions by automakers to not offer certain models as convertibles, due to the long product planning times involved and related expense, these government regulations were not really the culprit for declining convertible sales.

Logically, if there was consumer demand, the decrease in the number of convertible models offered would have actually led to an increase in sales for those fewer choices that remained. This did not occur at all until 1975 and 1976 when automakers announced the end of convertible production, notably the Corvette in 1975 and Cadillac the following year, and even then this may well have been due more to increased media and manufacturer attention to the end of convertible production.

I would suggest that the primary cause is more likely to have been the proliferation, and declining cost(at least in real terms or as a percentage of the total vehicle price), of good factory-installed automotive air conditioning systems. Here is an interesting article on the history of a/c in cars.

Followed by Danny Plotkin:

Those are insightful comments that square with my understanding. While air conditioning likely was a factor, it was still an expensive option. I think the availability of sun roofs had a role too, along with a newly developed consumer preoccupation with safety.

But above all I think it was economics. As convertible popularity waned manufacturers found building convertible versions on its assembly lines to be costly given the body structural modifications and other processes that were specialized for roofless cars. Some were farmed out to ASC and similar operations.

I think its fair to say that in the automotive arena, when a product or type disappears its almost always driven by the market and economics and not governmental regulation, actual or anticipated.

And finally, Terry Bowman:

I can name a lot of reasons for convertibles to fade away.
Heavy car (hard on fuel and slowed down the Hi-PO models)
expensive (body & doors had to be reinforce to keep from bending)
top rot (expensive to replace and never seems to fit right again)
leaks (check out the floor pans before buying a used one)
Easy to break into (box cutter or pocket knife will get you in every time)
I believe most did not come with AC (Bummer with the girls on a date), but will work on the way to the beach with them.
Who wants to pull over every time it starts to rain and put the top down (I’ve known some tried this while driving) bad idea.
Cleaning the interior is an on going project.
Ever want a bad hair day, this will do it. (Hope your gal didn’t just get her hair done)
Keep clear from Mud puddles while passing or being passed. (see cleaning interior)

Got any theories of your own? Let us know in the comments below.