The founders of Lyft, the ride-hailing service, have long imagined that the future of transportation would involve fewer cars on the road. Now General Motors is helping the start-up reach that goal.

Lyft announced on Monday that G.M. had invested $500 million in the company, or half of its latest $1 billion venture financing round. The funding, which recently closed, values Lyft at $4.5 billion, not including the new capital.

G.M.’s support includes more than financial backing. As part of the investment, G.M. and Lyft will work on developing an on-demand network of self-driving cars, an area of research that companies like Google, Tesla and Uber have all devoted enormous resources to in recent years.

G.M. will also work with Lyft to set up a series of short-term car rental hubs across the United States, places where people who do not own cars can pick up a vehicle and drive for Lyft to earn money. Daniel Ammann, president of G.M., will join the board of Lyft, which is based in San Francisco.