For years, scientists have dreamed of an efficient future where instead of owning your own car, you'll be able to call up a smart vehicle to your location, have it drive you to your destination, then allow it to continue on its way and pick up another passenger. The whole idea revolves around a gigantic network of driverless cars that serves millions of people on demand, minimizing waste in time and resources.

Now, General Motors wants to make that future a reality — by investing half a billion dollars in Lyft, the ridesharing company. The partnership, announced Monday, will initially see GM providing Lyft drivers with regular cars they can use to pick up passengers. And customers and drivers will be able to take advantage of GM's in-car connectivity services, like OnStar.

But the ambitious autonomous vehicle network is the cornerstone of the deal. It's a sign of intent to keep pace with Uber, Lyft's ridesharing rival that all but bought out the robotics team at Carnegie Mellon University last year. And with other carmakers striking Silicon Valley partnerships of their own — such as, reportedly, Ford and Google — we're beginning to see the rise of a whole new area of competition in the auto industry.

What began as a race to turn driverless cars into a mainstream technology is now moving on to its next stage, before the first has even finished. This next fight is all about shaping the business model of personal mobility — that dream-future of instant access to a personal taxi you don't have to pay to own.

"We see the future of personal mobility as connected, seamless and autonomous," said GM president Dan Ammann, in a statement.

Consumers will begin to see some fruits of the partnership immediately, such as the availability of GM-made cars on Lyft. The autonomous network, however, could take years; the companies haven't provided a timeline for that project.

By investing in Lyft, GM also gets a seat on Lyft's board — meaning it will gain a non-trivial level of influence over Lyft's decisions. While it's too early to say whether GM will be taking a hands-on role here, it's a big step beyond the in-house research and development that many automakers have been pouring into vehicle automation themselves.

In other words, GM is attempting to do more than conquer the basic engineering problem of designing a safe, working self-driving car. It's looking even further ahead, to try to anticipate the resulting economic and social changes that will almost certainly reshape their business model in affluent urban areas. By figuring out now how it might put millions of next-gen cars on the road and putting them to efficient use, GM seeks to gain an early edge on other automakers.

Urban driving is poised to change tremendously in the coming years. Although car sales will still rise as developing markets mature, autonomous vehicles and on-demand services will serve to slow that growth, according to an industry study published Monday by McKinsey & Company. As many as 15 percent of cars sold in 2030 could be fully autonomous, the study finds. One in 10 could belong to a sharing arrangement rather than being privately owned.

"Carmakers are definitely worried that their business model is going to be seriously threatened in the next 10 years," Karl Brauer, an analyst at Kelley Blue Book, said in an interview. In a statement Monday, he added: "Traditional car companies [are] scrambling to position themselves for an uncertain future."

Changes in car ownership are creating new challenges for automakers — but also opportunities. Even if the industry's sales start to drag, the cars that are on the road will still be racking up millions of miles a year. Ford chief executive Mark Fields has said that he wants to offer paid services designed to take advantage of all those vehicle-miles traveled, ones that will help complement the company's traditional business of selling actual cars.

"We're thinking of ourselves as an automotive company and a mobility company," Fields said at a conference last month. He added that in a future where autonomous cars are constantly shuttling people back and forth rather than sitting dormant in a parking space, those cars are likely to rack up miles "way faster than a private-use car."

Getting a head start on these issues may make all the difference for an increasingly cutthroat and high-tech industry.