Google this week invited journalists to inspect and ride in two prototypes that demonstrate the self-driving software it has developed so far, which can identify objects seen by sensors on or near roadways – whether that’s a stop sign, a child running from between parked cars or a fire engine – and instructs the vehicle how to respond safely.

This writer drove in both prototypes and was quite impressed. While the prototypes’ performance was hardly perfect, as my colleague Kirsten Korosec noted, they conveyed an artificial intelligence that already suggests itself to be superior in many ways to the distracted, impatient and often imprudent behavior of human drivers.

Most auto executives have predicted that a commercial autonomous car is a decade or more away. But Google seems to be on a path to have a self-driving car on the market far sooner. Chris Urmson, Google’s director of the self-driving cars division, was asked when, specifically, such a vehicle might be available for purchase, he indicated a four-year time horizon. “I have a 12-year-old son,” he said. “My goal is for him not to need a driver’s license.” In California, you can get a driver’s license at the age of 16.

In what was another clear sign of how high a priority the project is, Sergey Brin, Google president and co-founder, paid a surprise visit to the press briefing.

Interestingly, though, Google executives acknowledged that they don’t wish to build cars — but rather will partner with automakers to bring the project to fruition. “To bring this project to scale, we need to partner with top-tier OEMs (original equipment manufacturers – automakers),” Brin said. That, no doubt, will quiet the anxieties of auto executives from Detroit to Munich, though Apple Inc., another Silicon Valley enterprise that wants to get into self-driving car business, has made no such public assertion.

Earlier this month, Google hired as CEO of the project John Krafcik, an auto industry veteran and former chief executive officer of Hyundai Motor Co.’s North American subsidiary. Krafcik, no doubt, will begin forging formal alliances with automakers and major parts suppliers. Google’s technological progress, meanwhile, has lit a fire under the world’s automakers.

Auto executives and engineers increasingly discuss and demonstrate their own initiatives to develop technologies that take over for drivers in certain situations. Volkswagen AG’s Audi luxury vehicle subsidiary, for example, offers in its new Q7 large SUV an array of digital safety technologies. One, called traffic jam assist, allows a driver in slow, heavy highway traffic to turn over most of the driving to the car.

Traffic jam assist draws from a slightly older radar-based technology called “adaptive cruise control,” which is becoming more common on all automobiles. By integrating cruise control with radar, a vehicle may be set to drive at a certain speed and will automatically slow down when approaching a slow moving vehicle. An even newer feature, automatic emergency braking, can prevent most rear-end collisions.

As automakers develop more such features, they are advancing toward a vehicle that is very nearly autonomous. Yet automakers are achieving autonomy via a different route than Google, which is creating a “robot” that evaluates images and decides what to do.

General Motors Co. executives, meeting with investors at a business conference on Thursday, said they hoped to demonstrate an autonomous Chevrolet Volt extended range electric vehicle a year from now.

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Doron Levin’s postings on Twitter can be found @DoronPLevin. He is the host of SiriusXM’s “In the Driver’s Seat,” broadcast on Insight 121 on Saturday at noon and again at 9 a.m. on Monday.