Hertz will spend $68 million to add the hybrid cars by 2008, the Park Ridge, New Jersey-based company said today. The first 1,000 will be available at U.S. rental sites within the next few weeks, spokesman Richard Broome said.

“We want to meet expanding demand for highly efficient vehicles,” Broome said in an interview. Hertz now has only “a few Priuses, a few Ford Escape hybrids” for U.S. customers, he said, without elaborating.

Rental-car companies are offering more fuel-efficient, low- emission vehicles amid record gasoline prices and increased concern among consumers about global warming. Avis Budget Group Inc., the third-largest U.S. rental-car company, said yesterday that it’s adding 1,000 Prius cars. Hybrids save fuel by combining a battery pack and electric motor with a gasoline engine.

Hertz’s Prius order is among the largest, though Toyota won’t say whether any company or government fleet has placed a bigger one. “It’s a very significant purchase,” Toyota spokesman Bill Kwong said, without elaborating.

Prius sales in May reached a record 24,009, making it the ninth best-selling vehicle in the U.S. last month. The company has said it expects to sell at least 180,000 this year, or 68 percent more than a year ago.

Closely held Enterprise Rent-A-Car, the largest U.S. rental-car company, last week announced a plan to offer vehicles that run on alternative fuels and said it had more than 3,000 gasoline-electric cars for rent. The company will take delivery of 1,300 Prius cars by the end of July, spokeswoman Lisa Martini said in an interview today.