The future is now. And while we don’t have flying cars, vehicles of today are advancing at breakneck speeds. Case in point: technology being developed to monitor the health and well-being of drivers in an effort to reduce traffic accidents.

Developers and car companies are hard at work to cut back on distracted driving, from in-vehicle apps that stop you from using your cell phone, to technology that can sense when your mind (and eyes) are straying.

But at what point does your car’s concern become invasive or a violation of your privacy?

Cars that can analyze blood alcohol content

Currently, only drivers under supervision of the courts for previous drunk driving offenses are tested for alcohol consumption before turning the ignition. But in the near future, that may change.

Ignition interlock devices essentially prevent a vehicle from starting until a driver successfully passes a breath test. Autos of the future, however, may not require your breath.

According to a report from CNN, Nissan is working on technology that could detect alcohol in your sweat when you put your car into drive or shift gears. Also in the works is a navigation system that will detect if you are swerving or otherwise driving like someone who has had too much to drink.

The idea here is to increase traffic safety, but it isn’t clear how everyone will take to their car acting as a nanny.

Cars to detect distraction, sleepiness

The car of the future may be able to tell when you aren’t paying attention. While we commonly think of distracted driving as involving the use of a cell phone, distraction can come from something as simple as a pretty sunset.

Audi is looking at technology that can tell when you turn away from the road. Cameras focused on the head’s position would detect if the driver has looked away for too long. When this occurs, the vehicle could sound an alarm or even slow down to prevent a pending collision.

Drowsy driving, another major cause of serious car accidents, could be prevented by drivers making sure they get enough sleep. But car makers are perfecting technology that will sense when you are getting tired, through monitoring your eye movements and even your brain activity.

‘Invasive’ technology that could save your life

In addition to watching your head position and your eyes, your car could be taking far more invasive readings. Ford is working with health-technology companies to develop tools that would alert diabetic drivers when their blood sugar drops. Low blood sugar can lead to decreased mental clarity and even unconsciousness.

Ford has also developed tools that can monitor the outside pollen count and its effects on an asthmatic driver’s breathing. Electrocardiograph sensors could one day be placed in steering columns to sense the early signs of a heart attack—researchers in Japan are working on this now.

Accident prevention is taking a whole new direction as auto makers team up with technology. We may one day find that our cars do more to reduce the risk of an accident than the speed limit does—after all, who’s to say our vehicles won’t one day be able to sense the speed limit and adjust accordingly.

While all of these advancements are being designed with our safety in mind, there will no doubt be objections to some of the more invasive tools—like those that focus cameras inside the vehicle. As autos come with increasingly complex accident-prevention technology, a line will have to be drawn somewhere.

But, where does the line between accident prevention for the sake of all of us, and personal convenience or preference belong?