So-called "sudden acceleration" is an ugly mix of media frenzy, sophisticated engineering, and complex human-machine interaction.

But recent data on Toyota sudden-acceleration complaints seems to show--with some qualifiers--that the bulk of the incidents ending in fatalities have been reported by drivers aged 61 to 80.

Which leads to a very obvious question: Could it be that human error, not defective design, is at fault here?

Age clusters ...



This morning, our friends at Jalopnik posted a fascinating chart showing the age distribution of all the drivers in 56 deaths since 1992 that were linked by the Los Angeles Times to Toyota sudden acceleration.

And the chart is pretty revealing: The highest clusters are the 61-70 and 71-80 cohorts. The median age is 60, and just over half are 60 or older. That's against just 16 percent of drivers over 60 across all automotive fatalities.

They helpfully overlaid the average age distribution of deaths in all auto accidents, which peaks for drivers aged 22-30 and falls consistently thereafter. Death rates overall for drivers 61-80 are just one-third those of the 20-somethings.

Toyota's diagram showing how to properly install floor mats

... with caveats

There are several caveats. The data does not represent all incidents reported to the National Highway Traffic Safety Administration (NHTSA), because those reports do not specify the complainant's (or driver's) age.

Moreover, the age distribution of all sudden-acceleration complainants should be mapped against the age distribution of Toyota buyers overall, to ensure it's not representative. But we're pretty confident that the average Toyota purchaser is not between 60 and 80.

New York Times op-ed

But it's not just one of those durned auto blogs that suggests age plays a big role. Two media outlets have recently carried opinion pieces reinforcing the continuing belief among automotive engineers that driver error is largely to blame.

The op-ed page of The New York Times, carried a lengthy article last week by Richard Schmidt, a psychology professor at the University of California, Los Angeles, noting that driver error is almost always at fault in supposed sudden acceleration cases.

Based on his work in the 1986 Audi sudden acceleration case, he writes, "The trouble, unbelievable as it may seem, is that sudden acceleration is very often caused by drivers who press the gas pedal when they intend to press the brake."

Audi 5000 by Flickr user Mark.Mitchell.Brown

The Audi allegation

Toyota is likely haunted by the spectre of Audi's 1986 trials, when an inflammatory "60 Minutes" report led to scores of claims of so-called sudden acceleration. Audi's crisis management was a textbook case of what not to do--it clammed up, then it blamed drivers--but it was ultimately exonerated.

A long NHTSA investigation closed the books by saying the problem was "pedal misapplication," though it noted that Audi had spaced its pedal very closely together. By that time, Audi's sales had plummeted to numbers so low that the company almost pulled out of the U.S.

Audi subsequently installed an automatic shift lock, which prevents the car from being shifted into gear unless the brake pedal is pressed. Sudden acceleration incidents from standstill have plummeted in cars with shift locks, which Audi licensed to all carmakers.

[Overlawyered via Jalopnik; The New York Times; Los Angeles Times]

Wrecked Toyota Prius owned by Elizabeth James, photo by Ted James, from Houston Press

Psychological misfires

Schmidt notes that drivers 60 to 70 years old had complaints at six times the rate of those 20 to 30. Complaints were also more common among those unfamiliar with the car involved, and people of short stature. All cars involved had automatic transmissions.

How can a driver place a foot on the wrong pedal? Schmidt cites "noisy neuromuscular processes," in which a limb doesn't do quite what the brain tells it to, leading a driver's foot to deviate slightly from its intended path. Drivers misaligned in their seats raise the risk too.

In the panic following acceleration when the driver expected braking, the immediate response is to press down harder on the "brake" pedal, leading to further acceleration. Drivers, Schmidt says, "typically do not shut off the ignition, shift to neutral, or apply the parking brake."

Putting it into perspective



From the right-of-center Independent Journalism Project, Michael Fumento reaches the same conclusions, again citing the Audi precedent. He also notes the out-of-proportion response to what is, in reality, a very small number of deaths and incidents overall.

Loose all-weather floor mat jams accelerator pedal. Photo: NHTSA

Fumento wrote in the Los Angeles Times this week that the 56 deaths the paper cites over 18 years are just a miniscule fraction of the 420,000 total deaths in vehicle accidents during that period.

And he notes that no less a source than Edmunds.com found that Toyota's sales ranking--from 2001 to 2010, it was third in total U.S. car sales--was far higher than its ranking for number of safety complaints to the NHTSA, where it was 17th.

Villains: trial lawyers, media

While he doesn't attempt to explain sudden acceleration much beyond the Audi conclusion, he quotes Leonard Evans, author of a book called Traffic Safety, who notes that in general, "Most crashes occur because drivers don't leave an adequate safety margin."

Fumento blames an obsession with mechanical defects over drivers who observe safe following distances. And he slams "trial lawyers seeking the deepest pockets and a media that know it's sexier to crusade against corporations than emphasize individual responsibility."

President Bill Clinton

But back to age

Could the graying of Baby Boomers unwilling to admit they're aging even be a factor here? The earliest Boomers, born in 1945, are now 65--right in that high accident cohort.

TV shows and magazines are full of advice about how to take away the car keys from aging parents with failing driving skills. In an increasingly suburban United States, cars are a vital necessity, whereas earlier generations could walk or ride buses in central cities.

We'll leave it to the data to speak loudest. If investigators find no conclusive mechanical flaws, and the age distribution for so-called sudden acceleration is radically different from that for accidents overall ... then perhaps that disparity is worthy of investigation itself.

We will now take cover from the bombs and shells we expect to rain down from the AARP.

[Overlawyered via Jalopnik; The New York Times; Los Angeles Times]