Fully autonomous self-driving cars are still far from the market, but a wide range of features—including sensor systems that warn of lane departures and imminent crashes, and can even apply the brakes if you don't—are rapidly showing up in midmarket cars.

Take the Ford Taurus and Fusion: in 2013, you can get a radar system that senses if you are about to rear-end another car. It flashes red warning LEDs in the windshield, and even preprimes the brakes, building up pressure so that when you do tap the brakes, you'll get full stopping power.

These kinds of high-tech features have been available for years in luxury cars, especially high-end Mercedes and Volvo models. Now they're going mainstream. "It's the democratization of advanced driver assistance technology into high-volume cars," says Mark Boyadjis, a senior analyst for automotive research at IHS iSuppli. "The biggest trend is going to be these technologies finally making their way outside of the luxury space."

Beyond crash warnings and the related technology of adaptive cruise-control—which keeps you locked at a fixed distance behind the car in front of you when you've got cruise control switched on—there are ultrasonic systems that allow the car to sense a parking space and park itself, and cameras that keep track of lane markings, keep an eye on blind spots, and warn if you are about to bump into something while backing up.

The 2013 Honda Accord, for example, will get forward-collision and lane-departure warning systems and blind-spot detection systems. The Toyota Camry got blind-spot detection in 2012. GM's Chevy Equinox, Buick Encore, and GMC Terrain, along with the Dodge Charger and other Chrysler models, are among the models that started getting forward-looking collision-warning systems in 2012. "You see steps toward autonomous driving—that's exactly the transition that's sharpening, and that's what this is the beginning of," says John Capp, director of active safety technologies at GM.

Automakers are combining sensor data, too. GM, for example, is touting sensor fusion in its 2013 Cadillac XTS. While a front-mounted radar unit has an 18-degree field of view, allowing you to see another car cutting into your lane only after it's partway there, adding a camera with a 45-degree view angle and fusing the data provides earlier warning and smoother automated deceleration if necessary. "Camera and radar systems talking to each other are starting to show up on the marketplace, and this progression will go on," Capp added.