Why You Should Be Braking With Your Left Foot

Last week, I saved the life of a squirrel; let's call him Rocky. The nut-loving rodent darted out across the street, paused, then darted right back. I stopped short, missing the cute little guy by just a few feet. Rocky has no idea how lucky he really is, because if you're like well over 99% of the population, you'd still be cleaning parts of Rocky off your car.

I brake almost exclusively with my left foot -- a highly controversial practice -- and specifically because of that, no squirrel was squished. 

Left-foot braking has long been one of the most hotly contested topics in driving. Detractors claim it makes no difference at best, and is a horrible and dangerous practice at worst. However, you can stop 70ft faster in an emergency situation if you use your left foot properly (more on that number in a second). That's a potentially life-saving difference. I've said so before, and I'm saying it again: if you are in a new car, with an automatic transmission, then you need to brake with your left foot. 

Your foot's brake pedal accuracy is poor.

You don't control your feet nearly as well as you think

When you drive, you rely on muscle memory to operate your pedals. It's an incredible thing, really, that your body reflexively knows to lift up, move over, and press down with your right foot, all without conscious thought. That's actually part of the problem, though, as studies have shown time and again. Pedal location isn't standardized, so when you get into a car other than your own, the foreign pedal placement becomes a problem when your foot moves to its pre-programmed position.

But even if you never drive any other car but your own, there's still a significant margin of error when you lift your right foot up and move it over to the brake. The NHTSA had a great look at Pedal Application Errors, which included this beautiful nugget: "The farther the foot is from the intended pedal when the driver initiates a movement toward it, the larger the variable errors will be in hitting the pedal (due to the greater force). […] Faster movements to contact the brake pedal are likely to result in increased variation in the movement. This is particularly relevant when the driver makes a hurried braking response."

Translation: when you're stressed, your control over moving your foot is inconsistent. It's therefore a scientifically supported notion that when you've got your left foot covering one pedal, and the right foot covering the other, pushing your left foot straight ahead onto the brake reduces the capacity for error.

Left foot braking means shorter stopping times
Courtesy of GM

When you use your left foot, your stopping distance is dramatically shorter

I want to be clear here: the No. 1 factor in stopping distance at a given speed is reaction time, and by far the best way to cut down that time is to pay complete attention to the road around you. But even with zero distractions and a quart of coffee pumping through your veins, using your left foot to brake will save you valuable time (and thus distance) in an emergency.

A brilliant study from the University of Iowa establishes total driver reaction time as 2.2 seconds, and finds that the average driver will begin lifting his or her foot off the accelerator 0.96 seconds after the need arises. That means that the act of moving your foot over to the left, then pushing down on the brake pedal, requires an additional 1.24 seconds for that 2.2-second total. That's huge.

Meanwhile, it takes 1.64 seconds until drivers start to steer. Total. I'm willing to grant that it will take a fraction of a second to push down on the brake pedal even with your left foot, and I'll even go high here for the sake of argument, and allow that it's the same 1.64 seconds (total) to push on the brake with your left foot as it is to start to steer. Most people brake before trying to steer, so this actually skews the numbers, but the result -- saving 0.68 seconds -- is still absolutely convincing when you look at the distance that saves you over right-foot braking.

At 70mph, you cover 102ft, 8in per second. Over the course of the 68 hundredths of a second that a right-foot braker wastes, his or her car travels a full 70ft. Amazingly, that number (in feet) is going to remain tied to your speed in miles per hour. Going 45mph? You're saving 45ft with your left foot in an emergency, etc. Pretty cool, right?

Going back to our example with Rocky, when I missed him by around 5ft, I was going just over 40mph. He's welcome.

Don't keep your foot on the brake pedal.

But what about people that always have their brake lights on?

Some people do this, and they give left-foot brakers a bad name. There is absolutely no reason to ever rest your foot on either pedal. Keeping your foot poised above the pedal involves a process known as dorsiflexion, and if you're not used to it, your foot will get tired at first. This is why you see people driving down the road with their brake lights on -- it's simply someone who isn't used to it, and they're tired.

This applies to both feet, though, and if you're first starting out with your left-foot braking, you do need to be cognizant of what your right foot is doing, lest you have it pressed on the accelerator.

Even if you accidentally hit both pedals at the same time, you're still going to brake

By far the most common argument against left-foot braking stems from the fear of hitting both pedals at the same time. I spent hours trying to find data that supports this, specifically so I would have an answer for you. The truth is I couldn't find any supporting evidence that people actually hit both pedals. Even if I did find some, it wouldn't change the argument, because on newer cars mashing down on both pedals at the same time automatically cancels out the accelerator.

Braking with your left foot could have stopped this
Flickr/Joel Kramer

Can you hit the brake as hard with your left foot?

This is an interesting counterpoint. I've seen this theory a couple of times now, that by using your left foot against the dead pedal to brace yourself while braking with your right, you're able to put more force on the brake pedal. While I don't see hard evidence that this is the case, it stands to reason and I see no point in trying to refute it.

That said, it still doesn't get your foot to the brake pedal earlier. It also doesn't take into account how little brake pressure is needed in most of today's cars. Brake pedals are designed to be operated by even the weakest of drivers, which generally means you just need 100lbs of force to fully engage the brakes. I don't suspect that any realistic decline in brake force will offset the far greater distance in reaction time.

Minor rear end collisions should never happen.
Flickr/Anne Jacko

You were taught to brake with your right foot out of tradition, not data

Once upon a time, there were no such things as power brakes or automatic transmissions. People needed the left foot to work the clutch, and even if the transmission was in neutral, that whole bracing-yourself-to-hit-the-brake-harder notion would come into play. Clearly, it's not like that anymore, and it hasn't been for a very long time. On today's cars, even the notion that hitting the gas while you brake is dangerous is debunked. Cars have evolved. Your driving style needs to, too.

Should you start left-foot braking on your way home from work today?

That's a giant no. You've spent a long time getting used to braking with your right foot. The first time you try to stop with your left foot, there's a really good chance you'll slam on the brakes -- the amount of pedal force required to stop is a hell of a lot less than you think it is. Learn somewhere safe, like a parking lot. Practice there quite a bit, then progress to residential streets, just like when you learned to drive the first time.

Also, don't do this in a car with a manual transmission, since you need your left foot to push in the clutch.

One final caveat: statistically, the older you are, the more likely you are to have difficulty switching up your braking patterns. I started doing so in my late 20s, and it felt absolutely second nature within a couple weeks. If you're 50, it might not be so easy. Ideally, you'd learn from the first time you drive, but because some states will (incorrectly) fail you for using your left foot, you can't. You should still start teaching yourself the technique ASAP -- or don't cry to me when you rear-end someone.

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Aaron Miller is the Cars editor for Thrillist, and can be found on Twitter. He began braking with his left foot in 2008, and can't possibly fathom going back.