(CBS) If friends don't let friends drive drunk, there's one car that's a driver's best friend. It's equipped with a breathalyzer linked to the ignition, and it won't start if the driver is intoxicated.

"Interlock devices are up to 90 percent effective in reducing repeat offenses. This really can stop repeat offenders from continuing to drink and drive," says MADD CEO Chuck Hurley.

Now mandatory for repeat offenders in 19 states, ignition interlocks, as they're called, have been installed in about 100,000 cars. But that number is tiny compared to the 1.4 million drunken driving arrests made in the United States each year, reports CBS News transportation and consumer safety correspondent Nancy Cordes.

"We see them as a benefit — a technology that's being underutilized," says Nicole Nason of the National Highway Traffic Safety Administration.

But maybe not for long: At least four major automakers are working on their own versions.

Saab's AlcoKey, a key and breathalyzer in one, is already in field trials.

In Nissan's concept, sensors in the gearshift and seats would pick up alcohol in perspiration, whole a camera mounted on the instrument panel would detect drowsiness.

"They just touch or their regular breathing activates these systems, and they're able to warn them about their alcohol level," explains Bob Yakushi, Nissan's director of product safety.

It's still a good five years from reality.

For now, Steve Carter is using an interlock which he had installed after his third DUI.

"I'm not invincible, and if I continue behaving in this manner and drinking in this manner, it's going to kill me," he said.

While critics argue the technology isn't foolproof, highway safety advocates say otherwise.

"They're not that easy to defeat, but there's a perception out there that they are," Nason says. "They may have been in the beginning."

The devices have a track record, she says, for stopping would-be drunken drivers cold.

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