Skip to main content

The Danger of Too-Quiet Cars

Mandated Sounds for Safety Won't Arrive Until 2018

You can have too much of a good thing. Take silence.

When an electric or hybrid vehicle drives at low speeds, the lack of a combustion engine means it's quiet on the inside — and the outside, too.

While the driver and passengers probably enjoy the lack of noise, it's a danger for pedestrians who are walking close to these vehicles, experts say. The lack of familiar engine sounds jeopardizes the safety of blind and visually impaired pedestrians, as well as bicyclists, runners, small children, the elderly and anyone else who's on foot but generally not paying attention.

See Edmunds pricing data

Has Your Car's Value Changed?

Used car values are constantly changing. Edmunds lets you track your vehicle's value over time so you can decide when to sell or trade in.

Price history graph example

It's not a small issue, particularly for people with visual impairments. In 2012, 10 percent of adults — more than 20 million Americans — reported they have trouble seeing, even with glasses or contacts, or are blind. The Centers for Disease Control (CDC) estimates that more than 6 million Americans over 40 will experience low vision or blindness by 2030. That's double the 2004 figure.

Pedestrians are ubiquitous, and injuries and deaths involving them are climbing: 76,000 injuries and 4,743 deaths in 2012, a 6 percent rise over 2011. Of course, hybrid and electric cars make up less than 2 percent of vehicles on the road and so aren't the culprits in most of these incidents. But if hybrid and electric cars were equipped with engine sounds, and assuming that they will make up 4 percent of the 2016 fleet, the result would be 2,790 fewer accidents with pedestrians and bicyclists, according to the National Highway Traffic Safety Administration (NHTSA).

Long-Standing Safety Concerns
Concern about the safety of these groups of pedestrians and dangerous encounters with "quiet cars" dates back to 2003. That's when Deborah Kent Stein of the National Federation of the Blind "heard" a friend drive her new, quiet-on-the-outside Toyota Prius. It's what she didn't hear that shook her. "I couldn't hear any sound," Kent says. "It was an 'aha' moment."

Concern about a safety threat grew. By 2005, the federation was publicizing the issue and soliciting stories from its members about experiences they'd had with quiet cars. Soon articles began appearing in newspapers such as The Wall Street Journal. During the summer of 2008, NHTSA convened a conference with representatives from the blind and visually impaired communities, car manufacturers, policymakers and public interest groups.

After the conference, NHTSA conducted two studies. Each confirmed the dangers to pedestrians of silent cars driving at low speeds. A 2009 study said that at low speeds, hybrids and electrics were twice as likely as non-hybrids to be involved in a pedestrian crash. A 2011 NHTSA study found that pedestrian crashes were 35 percent higher with hybrids and electrics versus combustion-engine cars. A third study from the Highway Loss Data Institute studied seven years of pedestrian/vehicle crashes and concluded that hybrids are up to 20 percent more likely to be involved in injuring pedestrians than other cars.

A New Law To Require Alerts for Quiet Cars
Congress passed the Pedestrian Safety Enhancement Act of 2010 and it was enacted into law in January 2011. It mandates that the Department of Transportation create safety standards for car manufacturers to create a sound that alerts pedestrians to the presence of a vehicle moving at speeds less than about 18 mph.

Under the PSEA, the added sound must be "recognizable" as that of a motor vehicle in operation. NHTSA's Proposed Rule is projected to reduce the number of incidents in which EVs and HVs strike pedestrians. The PSEA regulation will require all new hybrids and electrics to have the audible alert system if they're manufactured on or after September 1 of the calendar year that begins three years after the date the final rule is issued.

Delays Push Final Rule Into the Future
Although the law was enacted in 2011, NHTSA has extended the deadline to accommodate comments from auto manufacturers and other groups. The Association of Global Automakers and the Alliance of Automobile Manufacturers urged NHTSA to defer full compliance until September 2018, citing concerns about the content of the final rule.

"We're very disappointed that the PESA's final rule hasn't been released," says John Pare, the National Federation of the Blind's executive director for advocacy, calling it a significant delay. "The number of silent cars continues to increase, only making the need for the rule that much more important to pedestrians," he said.

If you own an electric or hybrid vehicle without a noisemaker, don't expect to find aftermarket devices to address the issue. "It's not a priority," Pare says.

But that doesn't mean car manufacturers are doing nothing, says Chris Duke, who has 27 years experience customizing vehicles and hosts the auto improvement show Motorz. For example, Toyota and Lexus hybrid vehicles have a Vehicle Proximity Notification System. The top-selling electric car, the Nissan Leaf, has an alert noise, called the Vehicle Sound for Pedestrians. The plug-in hybrid Chevrolet Volt also has an alert noise, which the driver can activate.

But each original equipment manufacturer (OEM) is choosing how to proceed and what sound to include. The pedestrian alert on the Fisker Karma, audible when the car is in electric mode at speeds under 25 mph, sounds like a "combination of Tron light cycle, the 2001 monolith noise, the Droid phone commercial sound and a squadron of P-51 Mustangs banking overhead," wrote Dan Edmunds,'s director of vehicle testing. The sound of the 2015 Kia Soul EV is "part light saber, part slow-motion crickets," another reviewer wrote.

Meanwhile, though, "Some OEMs aren't doing anything until they know what the federal law says," says Duke. Ford is one of the carmakers that has not yet added warning sounds to its EVs and plug-in hybrids, company spokesperson Kelli Felker confirms.

Manufacturers want the alert sound to be pleasant to the ear of drivers and passengers, while avoiding a Pandora's box of too-divergent sounds, like individual ring tones for every vehicle. "Everybody's looking for NHTSA to come up with a solution so everybody can move on," Duke says.

Drive Carefully in the Meantime
Until at least 2018 or later, there's some simple advice for owners of hybrids and electric vehicles without external engine noise.

"Drive really, really carefully around pedestrians," says Stein. "Especially driveways, parking lots, school zones, cars pulling out of alleys — anywhere cars come in close contact with them."

Here's a piece of advice for pedestrians who are not paying attention: Quit staring at your smartphone while you're walking. Turn down the headphone volume. These are easy ways to avoid a close encounter with a silent-running EV or hybrid.

Featured new car releases

The 100% Electric BMW iX.

Discover the unprecedented power of the BMW iX.