I am embarrassed to say I'd never heard of them.
I knew about keyless locks, of course. And my parents still use one of those ridiculous steering wheel locks with the little rubber hook that supposedly deters thieves from taking your 2008 Nissan March.
Until this week, though, I'd never heard of an alcohol interlock.
It turns out the concept is simple ‐ in a car fitted with an alcohol interlock, you have to pass a breath test before the lock will release, the car can be started and you can drive off down the street.
The locks have been installed in the vehicles of more than 200 convicted drink-drivers.
And from the moment they became a sentencing option for Kiwi judges, in 2012, interlocks have prevented people from driving while boozed almost 2400 times.
Those numbers are incredible.
Without knowing exactly how intoxicated the drivers were when they tried to start their cars, crashes and fatalities have almost certainly been prevented.
And yet we could have done so much more.
An AA report shows that during the period interlocks have been available for sentencing, 12,000 repeat drink-drivers haven't had to install them in their cars.
Despite the convicted drivers being responsible for all interlock costs, the number of people sentenced to use them is embarrassingly small.
The Government is reviewing New Zealand's drink-driving penalties. I'd be delighted to see an interlock system become mandatory in every convicted drink-driver's car.
In fact, why not extend them beyond that? If we expect our vehicles to pass warrants of fitness and all passengers to wear seatbelts, would it really be that painful to install interlocks in all new cars?
It would cost no more than a few hundred bucks and a few seconds whenever you start your car. But think of the lives we'd save.
• Jack Tame is on Newstalk ZB Saturdays, 9am-midday.