Why some experts think driving with two feet could be safer than one

When we learn to drive, we're all taught to use the right foot for both the brake and gas pedals. But what if it's actually safer to use two feet?

A handful of experts, such as retired UCLA psychologist and ergonomics researcher Richard A. Schmidt, believe using two feet can solve a big problem: crashes that happen when a driver accidentally hits the gas pedal instead of the brake. Schmidt says these crashes are far more common than most of us realize — and the government estimates there are about 16,000 of them per year.

However, pedal error is a surprisingly controversial topic, and others say that many of these crashes actually result from cars' defective electronic systems and sticky gas pedals. But the bottom line is that this sort of error does cause at least some crashes. Schmidt and others argue that two foot driving could be a solution.

Two foot driving used to cause mechanical problems — but not anymore

(Shutterstock.com)

The prohibition against using your left foot for the brake originally came from the fact that all cars had manual transmissions — so the left foot was needed for the clutch. Nowadays, though, more than 96 percent of cars sold in the US are automatic, and the remainder are disproportionately sports cars.

The most often-cited reason that drivers of automatic cars should still use one foot is the idea that, if you use both feet and accidentally step on both pedals at once, you can do serious damage to your car — specifically, putting strain on the torque converter, transmission fluid, and brake fluid.

This was certainly true in the past. But after a series of high-profile defect-related unintended acceleration crashes — such as the ones that plagued Toyota vehicles in 2009, caused by floor mats and sticky gas pedals — automakers widely adopted a new technology that solves the problem.

These brake override systems automatically detect if both pedals are pressed down, and cut power to the engine if they are. They're now standard for the vast majority of new cars. And with both this technology and automatic transmission in place, there's not an obvious downside to using your left foot to brake.

Pressing the gas pedal by accident might be more common than we realize

(Mark Boster/Los Angeles Times)

The idea of hitting the gas pedal when you mean to hit the brake might sound far-fetched. But the idea is that you'd mistakenly put your foot down slightly more towards the right than you realized (not that you'd mix up which pedal is on the left and which is on the right). And while there hasn't been a ton of research in this area — most is decades old — data suggests it happens disturbingly often.

Schmidt originally came to the idea through his broader ergonomics research in the 80s, finding that when people repeatedly try to execute a simple movement over time (say, touching a stylus to a target on a screen), their force and accuracy varies by a surprising amount. He says those deviations are because of underlying neuromuscular variability and compares them to the slight randomness in movement that makes a top basketball free-throw shooter occasionally miss a shot.

Meanwhile, in the '80s, Virginia Tech engineering professor Walter Wierwille conducted the only experiments to date specifically on pedal error, filming participants in driving simulators. They were small-scale trials, but he was surprised to find that an average driver touched the wrong pedal surprisingly often. "An error might generally occur once every half-hour, or every hour," he told NPR in 2010.

Less serious errors — such as a driver briefly tapping the wrong pedal or accidentally pressing down on both pedals — happened much more often than someone stamping hard on the gas went they meant to brake.

But when someone does hit the gas instead of the brake, psychologists such as Schmidt believe our instincts can fail us, exacerbating the problem. In a 2010 New York Times op-ed, he described a hypothetical case:

Surprised that the car moved so much, he would try pressing harder. Of course, if his right foot was actually on the accelerator, the throttle would open and the car would move faster. This would then lead the driver to press the "brake" harder still, and to bring about even more acceleration. Eventually, the car would be at full throttle, until it crashed. The driver’s foot would be all the way to the floor, giving him the impression that the brakes had failed.

Admittedly, we don't have great data on how often this actually occurs. But Schmidt's 2010 analysis of decades' worth of North Carolina car crash data found more than 3,000 cases of it. And most happened during normal, unhurried conditions in which the driver simply touched the wrong pedal and kept pressing it harder, thinking it was the brake.

Other research by the National Highway Traffic Safety Administration suggests that older and shorter drivers are most likely to be involved in pedal error crashes, the latter because they have to reach farther for the pedals in the first place.

The frequency of pedal error is a very controversial topic, in part because it blames drivers for unintentional acceleration, rather than manufacturer defects. But whether or not it causes more crashes than defective electronic systems and sticky gas pedals, it certainly happens in at least some cases — and we might have a solution.

Is two foot driving the answer?

(Shutterstock.com)

The basic idea is that by using two feet to drive — one for the accelerator and one for the brake — drivers will be less likely to use the wrong pedal by accident.

Because you don't need to maneuver your right foot back and forth, you reduce the chance of an inaccurate placement. Each foot just hovers over a pedal, pressing straight down when needed. (And if somehow your left foot hovered over too far to the right, it would be pretty obvious because it would likely hit your right foot.)

Of course, there are a few reasons why this might not be a great idea for everyone. If you have some experience driving manual, your left foot is probably used to stamping down much harder on the clutch than is necessary for a brake pedal, a habit that might be hard to unlearn.

Additionally, because of the brake override systems, if you rest your foot lightly on the brake while accelerating, it could cut power to the engine when you don't mean to. For some people, it might be hard to keep the left foot entirely off the brake for extended periods of time.

Most importantly, we don't have hard data on how often pedal error occurs or experiments definitively showing that two foot driving can cut down on it. If you're happy driving with one foot, all this probably doesn't constitute a good enough reason to switch things up, which could make things more dangerous in the short term as you transition over to it.

But there are lots of drivers out there who actually feel more comfortable driving with two feet and have been told over and over that it can damage their cars. And that's simply not true.

Will you support Vox’s explanatory journalism?

We'll be honest: advertising alone isn't enough for Vox, or most newsrooms, to do the amount of high-quality journalism that the world needs and keep it free. We count on contributor support in order to produce nuanced, clear, and optimistic journalism. We don't have a paywall or ask our readers to subscribe in order to see our content, so instead, we’re coming to you this #GivingTuesday to ask you to make an investment in our future. If you’ve read an explainer this year that helped you to see an issue more clearly, got the answer to a long-time question, or just plain learned something, then we hope you’ll consider making a contribution of $20 or whatever you can today.

One-Time Monthly Annual

$5/month

$10/month

$25/month

$50/month

Other

$

Yes, I'll give $5/month

Yes, I'll give $5/month

We accept credit card, Apple Pay, and Google Pay. You can also contribute via