CLEVELAND — Higher gasoline prices won't be the only thing crimping family vacations this year.

Consumers will pay more to rent cars from companies such as Hertz Global Holdings Inc. and Avis Budget Group Inc., two of the largest in the U.S., as they pass along the rising cost of purchasing new vehicles for their fleets. Prices have jumped more than 20 percent the past two years and might increase another 5 percent in 2007.

Hertz and Avis now pay more for General Motors and Ford Motor vehicles because the two largest U.S. automakers have cut decades-old discounts to try to erase billions of dollars in losses. GM's February fleet sales — to businesses, rental-car companies and the government — dropped 18 percent from a year earlier.

"Consumers have gotten used to too good of a deal," said Neil Abrams, president of Abrams Consulting Group in Purchase, N.Y., which tracks the industry. "Rental prices were kept artificially low by the relationship with automakers. The practice made for irrational pricing."

Corporate rentals for business travelers aren't affected. They're negotiated at set prices, and because of the volume, their tab is more stable.

"Pricing tends to be highly volatile in the leisure market," said Kwame Webb, an analyst with T. Rowe Price in Baltimore, which owned 3.2 million Hertz shares in December. "Corporations can say 'This is my price. Take it or leave it.' "

That means it's the leisure renter who takes the hit. Hertz and Avis passed along higher vehicle costs to customers and then some, leading to increased profit and stock prices.

Shares of Hertz have jumped 51 percent since its initial public offering Nov. 15. Avis, in business since 1946 and formerly known as Cendant Corp., gained 46 percent since it began trading Sept. 4. The Standard & Poor's 500 Index has gained 12 percent since then.

Christopher Jarvis, 36, a financial consultant from Austin, Texas, said he rents a leisure car once a month. After primarily renting at Hertz, he now compares prices.

"I will now price-shop unless I have a time issue," Jarvis said.

The average daily U.S. rental price for a midsize car such as the Chevy Classic or Pontiac G6 on the first Monday in April was $48.56, 23 percent more than the same time two years earlier, Abrams said.