Yahoo Finance The brake pedal on your car is becoming obsolete
It used to take three foot pedals to operate a car—one for the accelerator, the brake and the clutch. The automatic transmission eliminated the clutch pedal for those who didn’t want it, leaving just two. And now, new technology could eliminate the need to use the brake pedal in most driving situations.
The new Chevrolet Bolt, which will hit showrooms later this year, will be one of the first models to offer “one-pedal driving:” an accelerator that makes the car go faster when you press it, as usual, but also slows the car down when you ease off and brings the car to a full stop when you're off the accelerator completley. “In stop and go traffic, when you want to stop, you take your foot off the accelerator,” Pam Fletcher, General Motors’ (GM) electrification chief, tells me in the video above. “It makes it very easy, very convenient, in congestion.”
Most cars today exhibit the “sail-on effect” when you take your foot off the gas: They keep rolling, slowing down only gradually on account of friction and, sometimes, the resistance of whatever gear they happen to be in. With one-pedal driving, the car decelerates much more rapidly when you let off the gas, almost as if the car is braking itself. There’s still a brake pedal, but much of the time you won’t have to use it.
One-pedal driving is a feature limited to cars with an electric motor that captures energy from the spinning of the wheels, a process known as regeneration, or “regen.” Regen can happen in a number of different ways, depending on how the automaker chooses to tune the car. In a Toyota Prius hybrid, for example, regen captures energy that goes back into the batteries, but it doesn’t decelerate the vehicle. The driver might be sitting on new technology, but the driving sensation is entirely familiar.
The Bolt, in normal “drive” mode, operates the same way. But GM decided to add a “low” mode that entails much stronger deceleration. And there’s a paddle on the steering wheel that intensifies deceleration even more. “You can literally drive all the way home without touching the brake,” says Josh Tavel, chief engineer on the Bolt, who drives a prototype model as his family vehicle. “I rarely use the brake.”
One-pedal driving—also featured on the BMW i3 electric, which starts at around $43,000—takes some getting used to. “Most people don’t like it at first,” says Tavel. “After a while, some absolutely love it, while others never get used to it.” The most startling difference is how sharply the car slows down and comes to a full stop when you take your foot off the accelerator, instead of just rolling along like a traditional car. Most drivers halt far short of their intended stopping point when they first experience one-pedal driving, because they underestimate the stopping power of regen. A little practice makes for smoother stopping.
The Bolt will have four different driving modes, ranging from completely normal to completely one-pedal, since you can cruise in drive and low and use the paddle to intensify deceleration in each mode. Average braking in a normal car applies about -0.15 G forces to a vehicle. In low, the Bolt will decelerate at about -0.22 Gs, without the brake. In low mode with the paddle engaged, deceleration rises to about -0.3 Gs without the brake. That’s enough to handle most braking situations for a driver determined to stay off the left pedal (which EV drivers have a way of getting competitive about).
Emergency braking requires forces up to about -1 G to bring a car to a quick halt, which is well beyond the deceleration available in the Bolt's low mode. That’s why the Bolt’s traditional brakes will always be available, no matter what driving mode the car is in. Software, meanwhile, makes the brake lights go on when deceleration hits a certain threshold, even if you never touch the brakes. And on the highway, there’s less deceleration when you ease off the gas in low mode, since that’s when drivers more likely just want to cruise.
In addition to one-pedal driving, most automakers are rolling out automated braking systems (totally different), which use sensors to detect hazards and apply the brakes automatically if you get too close to a car in front or some other obstacle. Those sytems aren't limited to electrics and are beginning to appear on a variety of models. So traditional braking is changing in other ways, too.
The extent to which one-pedal driving catches on will obviously depend on how widespread electric vehicles become. For all the hype they’ve generated, EVs still represent far less than 1% of all vehicles on the road. One barrier is cost. The Bolt, while one of the more affordable electrics, will still start at around $37,000 (before tax credits) when it hits showrooms later this year.
Automakers are enthused about the technology, however, with many saying the cost of batteries and other components is falling quickly. And EV enthusiasts praise the quick pickup and sporty handling electric powertrains can provide, along with the convenience of fueling at home. One-pedal driving may be one more reason to sing the praises of electric technology—or at least differentiate it from the boring old gas-powered engine.
Rick Newman’s latest book is Liberty for All: A Manifesto for Reclaiming Financial and Political Freedom. Follow him on Twitter: @rickjnewman.
