FORTUNE — Self-driving cars may be closer than anybody realizes. Cadillac is rolling out high-tech options for two new models this year which provide — however brief — a glimpse into a future where computers take over from drivers.

An array of new sensors, warnings and automatic controls can already help drivers detect hazardous situations and avoid accidents, according to General Motors Co. (GM) engineers. Eventually, by bundling navigation and decision-making algorithms with such systems, GM believes a self-driving car is feasible. The automaker said the first version of a “semi-autonomous” car might be available by mid-decade and a more advanced version by the end of the decade.

While new advanced safety systems aren’t a panacea, they will no doubt provide a backup to drivers who doze off or whose attention wanders while using the phone, drinking coffee or scolding the children. “There still are issues that must be solved, specifically how to keep the driver’s attention engaged as more of the car’s functions become automatic,” says Alan Taub, who is retiring next month as head of GM research and development. “The autonomous car is quite real and closer to reality than many people think.”

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In January, Audi announced at the Consumer Electronics Show that it is “actively developing” and intends to offer “by mid- to late-decade” a system that will allow drivers in slow-moving heavy traffic, such as on the freeway, to switch to a semi-autonomous mode that will keep the car moving in its lane at a reasonable speed while preventing it from hitting another vehicle. The feature likely will appear first on Audi’s A8 flagship sedan.

Last year, Nevada became the first state in the U.S. to adapt its laws so that driverless cars may operate on its roads. Google (GOOG) has famously experimented with a self-driving car, as has the tiremaker, Continental.

In March, I was among several journalists invited to GM’s Milford, Michigan proving grounds for a briefing on autonomous driving, including demonstrations of several technologies and systems. By far the most dramatic was a “drive” behind the wheel of a specially outfitted Cadillac SRX to show the capability of its “Supercruise” semi-autonomous capability.

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With a GM engineer in the SRX front passenger seat, I accelerated to about 60 miles an hour and activated Supercruise. With my hands off the wheel, the car maintained the proper speed and didn’t stray from its lane. Soon a driver in another GM test car approached from the left and cut in front of my car, into my lane. My car slowed down, keeping a safe distance behind it. Once it left, the car sped up again.

Next the car cut into our lane from the right. Again, our car — using LIDAR, a sensing system that employs light waves — avoided the second car without any jarring or abrupt actions.

The two new Cadillacs, the large XTS and the compact ATS, will offer packages that include adaptive cruise control, which adjusts to the speed of vehicles ahead; backup warnings that tell when vehicles are approaching from the side; a warning indicator to tell if a vehicle is in the blind spot, lane departure warnings, braking assist and others. Similar technologies and features already are available on several models of Mercedes, Audi, BMW, and Lexus (TM) vehicles.

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A “safety seat alert,” transmitted via vibrations from the driver’s seat, indicating hazardous situation, such as lane departure on the right or left part of the seat will be a first for GM. Vibrations are transmitted via the driver’s backside. The system works in tandem with warning lights on the dashboard. GM said the vibration is more effective than a chime or buzzer, which some driver’s may not hear or find annoying.

In any event, late-night comedians will have fun with GM’s vibrating seat concept if it becomes popular.