Would You Trade Lower Insurance for An In-Car Breathalyzer?

Four friends killed in head-on collision in San Diego County

I've been wondering about drunk driving and how it could be addressed in a more proactive and preventive way. My latest idea comes as a result of reading the linked article above. The short story is a likely intoxicated guy veered into oncoming traffic in his Yukon (big ass truck) and killed four people in a Camry.

Why not offer lowered insurance rates for cars that get equipped with a breathalyzer that's connected to the ignition. Blow safe or the car doesn't start.

It'd be mandated for previous offenders but people who just wanted a break on rates and maybe prevent their drunker and dumber selves from killing four people.

How much would it have to save you per year before you'd let them install one?