Yesterday I bumped into another old story that knocks around the car world: In the 1960s, Porsche feared that upcoming roof crush rules in America would outlaw convertibles, and Porsche made the Targa with an integrated roll hoop to sidestep it. The story goes that these rules never came into place. That’s both not true, half true, and filled with car companies doing what they know best: helping Americans die.
I’ll quote from Automobile Magazine’s history of the Porsche Targa, published earlier this year, as a good example of the story car people tell each other:
In the late 1960s, a rumor blew across the Atlantic from the U.S.-even then one of Porsche’s largest markets—and it said the convertible was headed for an uncertain future. Proposed future safety regulations being considered by the Department of Transportation suggested convertibles were simply too dangerous to continue building for American roads. Without racing-style rollover equipment, a rolling crash in a convertible often had fatal consequences, especially in a time when many drivers on the road still failed to even wear safety belts.
Though the proposed legislation never came into existence, it posed a serious enough threat that Chevrolet added a “T-top” model with twin roof panels split with a central hard bar to its C2 Corvette lineup in 1968, hedging against the possibility that convertible models could no longer be sold.
This is the kind of story that immediately rings like a tall tale. There’s some mysterious unnamed law that gives way to a fortuitous auto company ending up with a cool car through its noble actions. It’s the kind of story that gets repeated because it sounds good for the car company and sounds sly for the teller.
Of course it’s incorrect, though it’s not totally wrong.
The legislation did come into existence, just not as Porsche and others feared. That legislation would be Federal Motor Vehicle Safety Standard (FMVSS) 216. FMVSS 216 is still on the books, and deals with “Roof Crush Resistance.” I found this all out this afternoon after some cursory Google searches, most of which took me about half an hour. One thing you find out when you study history is that there’s not actually all that much secret out there; it’s just that people in power don’t like repeating stories that don’t make them sound good. And there’s not a lot in the history of FMVSS 216 that makes anyone sound good.
What FMVSS 216 does is ensure the strength of a car’s roof so that it doesn’t crush you if the car flips over. Here’s how the law itself reads:
FMVSS 216, Roof Crush Resistance, establishes strength requirements for the passenger compartment roof of passenger cars, multipurpose passenger vehicles, trucks and buses with a GVWR of 2722 kilograms or less. The purpose of the standard is to reduce deaths and injuries due to the crushing of the roof into the passenger compartment in rollover accidents.
What does FMVSS 216 not apply to? Convertibles! It’s right in that same paragraph:
It also does not apply to convertibles, except for optional compliance with the standard as an alternative to the rollover test requirements in S5.3 of FMVSS 208.
FMVSS 208 is the catch-all of car safety regs. It covers everything, and here is S5.3, via Cornell:
S5.3 Rollover. Subject a vehicle to a rollover test in either lateral direction at 30 mph under the applicable conditions of S8 of this standard with a test dummy specified in S8.1.8 placed in the front outboard designated seating position on the vehicle’s lower side as mounted on the test platform. The test dummy shall meet the injury criteria of S6.1 of this standard.
I suppose this explains why you see convertibles with deployable rollbars.
Now what’s interesting is that FMVSS 216 is still static, and not a dynamic rollover test. Why is this? Because the Big Three lobbied against it, even though they had evidence to the contrary.
Now, thousands of Americans die every year in rollover crashes (more than 7,600 in 2010, per NHTSA) so it comes as no surprise to me to see a discussion of FMVSS on a law firm’s website. This is a nice breakdown on how Chrysler, GM, and Ford worked against rollover safety, as published by Beasley Allen:
FMVSS 216 was not approved as originally proposed.
The test was modified, prior to final approval, to provide for testing of only one side. The load could be applied to either side; and both sides must be able to withstand application of the load. However, the load was not applied sequentially to both sides in the same test. The problem is that the application of the force to one side may weaken the roof structure. If the roof structure is compromised with the first application, the other side will lose strength and not be able to withstand the same amount of force, leading to the collapse of the roof structure. To verify that a roof structure is sufficiently strong enough to withstand sequential impacts as are experienced in a real-world rollover, the vehicle must be tested with sequential loads. FMVSS 216 is a static test in that the vehicle does not move during the testing.
Prior to the development of the static test, the automakers used dynamic tests to verify roof strength. One such dynamic test was the inverted drop test, in which a vehicle was suspended upside down and dropped onto its roof from 6 inches to 2 feet. It is important to note that in the late 1960s, many of the vehicles being manufactured showed serious roof collapse in inverted drop tests. The same vehicles also failed the government’s proposed two-sided static test. Their vehicles, however, could pass a standard that tested only one side with the pitch angle reduced to 5 degrees.
Internal and public records show that GM, Ford and Chrysler lobbied to eliminate the sequential testing to the second side of the roof and reduce the pitch angle for a roof strength safety standard their vehicles could pass. This test became our government standard in 1973 and it is the same standard we have today.
Beasley Allen goes on to note how the Big Three cited research from Cornell that backed up their positions that roof crush standards need not be as strong as the government wanted, but that the Big Three were “financially supporting” Cornell at the time.
Now, FMVSS 216 has slowly become more strict over the years, and rollover deaths have fallen by a few thousand since the 1970s, per NHTSA data compiled by IIHS. So much has changed over these years with regards to rollovers. We saw the SUV boom of the 1990s and 2000s drive up total rollover deaths, and we have seen airbags and electronic stability systems drive them down, as noted by NHTSA research in 2018.
What hasn’t changed much is what percentage of deaths are from rollovers. In 1978, rollovers were 27 percent of passenger vehicle occupant deaths. In 2018, it was 29 percent. And the deciding factor in if you live or die, according to a NHTSA study from 2000, is if you’re wearing a seatbelt or not. A solid 72 percent of people who died in rollover crashes in the midst of the SUV boom were unbelted. Updated NHTSA data from 2010 shows that figure holding strong at 69 percent.
In 1974, just a year after FMVSS 216 became implemented, the federal government started enforcing another rule: seatbelt interlocks. If you weren’t belted, your car wouldn’t start. This is tech that has been refined and is still available today, but was reviled when it was new and bullied off the books.
So even after all of the lobbying, the biased studies, the secret research, it’s unclear just how much FMVSS 216 is what’s saving anyone’s life out there so much as just, well, wearing a seatbelt. Something we could easily make all cars require of their occupants. Instead we leave that job up to police enforcement, and we know how that has been going.