LAS VEGAS — The first major trade show of the year for the automotive industry used to happen in Detroit. But not lately.

These days, the world’s biggest carmakers spend the first week of January in the desert, at the giant consumer electronics trade show known as International CES. It makes sense, considering that today’s automobiles are the most sophisticated digital devices that most consumers will ever own.

And the same Internet-based technologies that have transformed computing and telecommunications are now disrupting the auto industry. The rise of ride-sharing, short-term rental services like Zipcar, cellular data links that connect vehicles to the Internet, and the impending introduction of self-driving cars have spawned a realization among automakers that soon, people may no longer need to own cars at all.

So carmakers at CES are preparing for a future in which automotive mobility is a service rather than a product, and cars — or even taxis — drive themselves.

General Motors Corp. set the tone Monday, announcing a $500 million investment in the ride-hailing company Lyft. GM and Lyft say they’re going to build a new service that will use self-driving GM vehicles, rather than human drivers.

On Tuesday, Ford Motor Co. described its own pilot ride-sharing program, tested in London and several US cities last year, in which owners of Ford vehicles could rent them out for short periods to preapproved drivers.

Ford chief executive Mark Fields said his company was moving to become “an auto and mobility company.’’ Instead of just making cars, he said, Ford plans to offer transportation services for a generation of customers who may prefer to borrow vehicles rather than own them.

“Those two companies are signaling that they understand that it’s not about moving metal any more,’’ said Frank Gillett, an automotive technology analyst for Forrester Research in Cambridge. “It’s about having an ongoing relationship with the customer.’’

In the future, Gillett said, people might become loyal Ford or GM customers simply by repeatedly renting one of their cars, without ever owning one.

Ford would not comment Tuesday on reports published in December that the two companies would team up on the manufacture of the self-driving vehicles Google has been developing.

But Ford did announce a partnership with Amazon.com, to include the company’s Alexa speech-control technology in its Sync vehicle voice control system. Amazon introduced Alexa last year in its Echo personal assistant device, which can play music or news broadcasts at users’ requests. Amazon plans to add Alexa to a host of household devices — appliances, televisions, home security, and heating and air conditioning systems.

Fields said when Alexa-enabled Ford cars become available later this year, a driver can use it to communicate with his home, turning up the heat, for example, or opening the garage door.

Meanwhile, Toyota of America described its new billion-dollar smart vehicle research initiative, headed by Gill Pratt, who previously headed robotics research at the Pentagon’s Advanced Research Projects Agency.

Toyota has recruited an exceptional array of talent, including two professors at the Massachusetts Institute of Technology, John Leonard and Russ Tedrake.

Last year, Toyota announced a $50 million investment to set up research facilities at Stanford University and MIT. The Cambridge facility, in Kendall Square, is under construction.

Tedrake said his research would focus on efforts to make self-driving cars “fail-safe.’’ That means that if the car malfunctions, it does so in a way that doesn’t hurt people.

“I think it’s an incredibly hard problem,’’ said Tedrake, because it’s impossible to predict all the circumstances that could cause a self-driving car to make a mistake.

For example, he said the vehicle might normally “see’’ a pedestrian in the road, and stop before hitting him. But if the same person is wearing a color that’s hard for the car to detect under certain lighting conditions, the vehicle might not stop.

Tedrake said he and his team will work to develop simulation software that can identify such problems in advance, and come up with solutions before they arise in real life.

For virtually everyone at CES, talk of self-driving cars has lost its “gee-whiz’’ tone; they’re now regarded as inevitable.

J. Gary Smyth, GM’s executive director of global research and development, predicted self-driving cars will be immensely popular with millennials, many of whom he said regard driving as a distraction, and with elderly and disabled people who’ll get a new measure of mobility.

But what about those who cherish the experience of driving? Smyth said his company’s cars would still offer drivers the option to take the wheel.

“There will be times when you will want to drive your car, when you will love doing it,’’ said Smyth. “And you will always have that opportunity.’’

Hiawatha Bray can be reached at hiawatha.bray@globe.com. Follow him on Twitter @GlobeTechLab.