PARK RIDGE, N.J. - Ford Motor Co. might have to increase its $30-per-share offer last month to buy the 18.5 percent of Hertz Corp. it doesn't already own, according to investment analysts. The current offer, which would cost Ford about $598 million, is being reviewed by a committee of three independent Hertz board members.

After a third-quarter profit warning, Hertz stock was trading at $24.25 before the Sept 21 offer, representing a 24 percent premium. But analysts note that Hertz stock was as high as $51.75 during the past year, and Salomon Smith Barney analyst David Reidel told financial Web site SmartMoney.com "it's highly unlikely" shareholders will settle for a price lower than the mid-$30s.

A $40 bid, which would value Hertz at 11.7 times consensus 2001 earnings estimates, would cost Ford about $798 million. When Ford spun off Hertz in 1997, shares opened trading at $24, a price-to-earnings ratio of 12.9 based on 1997 earnings.

The proposed buyout follows a major management shake-up at HERC in which several top-level executives have left the company, including vice president of sale and marketing Willie Swisher, who has joined online marketplace RentOnTheDot as president.