(Bloomberg) -- Uber Technologies Inc. is working withGeneral Motors Co., a major backer of ride-hailing rival LyftInc., to help drivers get access to vehicles.

The automaker's Maven car-sharingservice will let Uber drivers lease cars from GM'sfleet in San Francisco.

Test program

GM's Maven unit will test the program with Uber in thestartup's hometown for 90 days. GM is interested in expandingthe business with Uber after that period, said AnnalisaEsposito Bluhm, a spokeswoman for the automaker.

After the Detroit car company introduced Maven early thisyear, it signed a partnership with Lyft to provide short-termrentals to those who pick up passengers throughthe app. GM initially picked Lyft, in part, because Uberhad little interest in working with a major carmaker, said aperson familiar with the matter.

As Uber began to grow fast, raise capital from Toyota MotorCorp. and sell its China business for a stake in ride-hailinggiant Didi Chuxing, GM started to look at hedging itsbets, said the person, who asked not to be identified because theconversations were private.

"Lyft would prefer GM didn't do this because it's going tomake it easier for Uber to expand," said Evan Rawley, aprofessor at Columbia University's business school. "GM hasgot to think about their main business, which is selling cars."

GM will continue renting cars to Lyft drivers in SanFrancisco and a half-dozen other cities, Bluhm said. The companiesare also working together on experiments with self-drivingcars. "Our investment in Lyft is about autonomous driving,"Bluhm said. "The fact that we have attracted both Lyft and Uber isa strong sign for Maven."

Lyft's rental program, called ExpressDrive, also works with Hertz Global HoldingsInc. “Similar to how we work with Hertz and Maven onExpress Drive, it's expected that vehicle access programs havemultiple partners,” Sheila Bryson, a spokeswoman for Lyft, wrote inan email.

Attract drivers

Uber and Lyft use auto rentals and financing to attract andretain drivers, a key component of the fight between the twocompanies. They appeal to people without cars who wantto earn money through the apps. The programs areexpanding quickly, but critics have said they takeadvantage of people with bad credit.

In January, GM said it invested $500 million in Lyft thisyear, and Dan Ammann, the automaker's president, joined thestartup's board. The companies later held informal discussionsabout an acquisition, Bloomberg reported in August. The talksdidn't produce a deal, and Lyft co-founder John Zimmer has said hiscompany isn't for sale.

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