Over 15 years, as older cars without a so-called alcohol ignition interlock come off the roads, sobriety-screening systems in new vehicles could avert more than 59,000 crash fatalities, more than 1.25 million non-fatal injuries and over $340 billion in injury-related costs, the study in the American Journal of Public Health concludes.

"Alcohol interlocks are used very effectively in all 50 states as a component of sentencing or as a condition for having a license reinstated after DUIs, but this only works for the drunk drivers caught by police and it doesn't catch the people who choose to drive without a license to avoid having the interlock installed," said lead author Dr. Patrick Carter, an emergency physician with the University of Michigan Health System in Ann Arbor.

Most drunk drivers make about 80 trips under the influence before they are stopped for a DUI, Carter said. "If we decided that every new car should have an alcohol ignition interlock that's seamless to use for the driver and doesn't take any time or effort, we suddenly have a way to significantly reduce fatalities and injuries that doesn't rely solely on police."

Carter and colleagues used U.S. records of traffic accidents and fatalities to determine how many involved drunk driving and then estimated how many of these incidents could be avoided in the future by fitting new cars with alcohol-interlock devices, which detect blood-alcohol levels and prevent drivers above a certain threshold from starting the car.

Then, they estimated the numbers of deaths and injuries that could be prevented in the first year that all new cars sold had screening systems, and assumed it would take 15 years for older models to be replaced with new vehicles.

Over the 15-year implementation period, interlocks may eliminate about $343 billion in costs from fatalities and injuries related to drunk driving, the researchers estimate. Assuming the device costs $400 per vehicle and is 100 percent accurate, the interlock would pay for itself after three years by way of avoided injury costs.

"The technology is at this point pretty strong, and when implemented at a population level will be negligible in terms of the sticker price of a car," said Jacob Nelson, director of traffic safety advocacy and research for AAA. To be widely adopted, it will need to be a rapid test that's reliable and doesn't inconvenience drivers, added Nelson, who wasn't involved in the study.

The screening tool to do this is still in development, and may not be road-ready for another five to eight years, said Dr. Bud Zaouk, who is working to develop the technology, known as the driver alcohol detection system for safety, or DADSS. It would prevent a car from moving if the driver has a blood alcohol level of 0.08 or greater - the legal limit in most states - and could be set to zero for drivers under the legal drinking age.

“Unlike the alcohol ignition interlocks which require you to blow into a devise and are used for convicted drunk drivers, DADSS is a driver assist system that would be seamless, take less than half a second, and use infrared light to measure a driver’s blood alcohol content in the breath or through the fingertips, which is far more reliable,” said Zaouk, DADSS Program Manager and Group Director for QinetiQ North America, who wasn't involved in the study.

Getting DADSS into all vehicles can eliminate the element of chance involved in catching drunk drivers under our current system that relies on police, said Adrian Lund, president of the Insurance Institute for Highway Safety.

"It's so hard to catch everybody," said Lund, who wasn't involved in the study. "With this, we can stop them from driving in the first place, and we can catch a broader group of people who are getting behind the wheel because they think they're not impaired."