A glass of alcohol next to a set of car keys.

A new study from the Insurance Institute for Highway Safety (IIHS) estimates that putting alcohol detection technology in all cars has the potential to save more than 9,000 lives per year.

Anyone with a driver’s license knows that alcohol- or drug-impaired driving is illegal. Yet according to the National Highway Traffic Safety Administration, more than 10,000 people are killed in crashes involving drunk drivers every year. That’s nearly 30 percent of all motor vehicle fatalities, a percentage that has remained static every year over the last decade.

“This analysis shows a critical way to prevent road deaths, and we need to get rules on the books now,” says William Wallace, Consumer Reports’ manager of safety policy. “There's no need to wait. Congress should direct NHTSA to require new cars to come with drunk driving prevention technology." 

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The type of alcohol detection technology CR highlighted in a report (pdf) released recently is designed to operate much like the ignition interlock devices many court systems require convicted drunk drivers to install in their vehicles. A sensor detects the amount of alcohol on the driver’s breath, and if he or she is over the legal limit, the car won't start. Unlike interlock devices, though, newer alcohol detection technology measures blood alcohol concentration (BAC) through normal breathing from the driver’s seat. No additional steps are needed.

Auto manufacturers are engaged in a public-private project with NHTSA, states, and others called the Driver Alcohol Detection System for Safety (DADSS) to develop or explore this technology, and there's already road testing happening. Chuck Farmer, IIHS’s vice president of research and statistical services, says that although the sensor is passive—there’s no need to blow into it—it can distinguish the driver from other passengers in the vehicle by proximity. In other words, a sober designated driver shouldn’t worry about intoxicated passengers disabling the car. 

“You shouldn’t even notice it’s there unless it keeps your car from starting, and it should only do that if the driver’s blood alcohol level is above the legal limit,” says Farmer. “It has to be seamless and reliable, otherwise the public won't accept it.”

Based on crash statistics covering 2015-2018, Farmer calculated that 9,409 lives per year could have been saved if the BAC of the most intoxicated drivers had been below 0.08, which is the legal limit in most U.S. states. Using a standard formula derived from more than 50 years of research into impaired driving, he estimated that more than 10,500 deaths per year could have been avoided if these drivers’ BAC was below 0.05, and nearly 12,000 lives would be saved if the drivers had been completely sober.

In other words, a lower BAC correlates with a reduced risk of crashes, injury, and death. That’s why in the late ‘90s—when drunk driving deaths comprised nearly 40 percent of motor vehicle fatalities—the federal government threatened to withhold highway funds from states that refused to lower their legal BAC limits for driving to 0.08. Today, every state but Utah has a 0.08 limit. Utah lowered its legal limit to 0.05 at the end of 2018.

Still, the number of deaths involving alcohol-impaired drivers hasn’t changed much over the past 25 years, says Farmer. The reason: Aside from extreme cases, it’s difficult for law enforcement officers to tell who is and isn’t intoxicated. According to the IIHS study, fewer than 1 in 50 alcohol-impaired drivers are caught and arrested.

“Unless they're really weaving, the police might not see it, and someone who is too impaired to drive is going to get away with it,” he says.

Farmer conceded that it could take 20 years to install alcohol detection devices in all cars on the road, a factor that would limit the technology’s impact in the near term. If manufacturers were required to install the devices on all new vehicles starting now, he says, it would only achieve about half of its life-saving potential within 12 years, preventing just under 4,600 deaths per year. That’s still a lot of lives lost to drunk drivers.

“We’re seeing the same thing year after year—people aren't responding to drunk driving laws,” he says. “So if we can't change people, it's time to change the vehicle so that it will not respond to an impaired driver."