Traveler's Aide: I reserved a rental car, why isn't it here?

— -- Question: I made a reservation with Hertz to pick up a car in September at the San Francisco location on Mason Street. When I arrived at the office, I saw many people sitting on their suitcases and waiting. I was told Hertz would not have any cars for five hours.

When I asked why they could not honor my reservation, they told me they "overbook just like the airlines." I also asked why did they not call my cellphone, which was on file with my reservation. The answer was "we just don't." They said the problem was caused by a big Intel convention in town.

I walked back to my hotel, where the concierge was able to get me a car at Budget which cost more than my Hertz reservation.

I e-mailed Hertz customer service twice. The second time I received a response after more than two weeks. Hertz apologized and offered $50 in vouchers for a future rental, but I'm still out the price difference between the rentals. Can you help?

—Steve Strauss, Corona del Mar, Calif.

Answer: Many travelers have had the irritating experience standing around, waiting for their rental cars. But five hours? That's unreasonable by anyone's standard. Hertz agrees.

Car-rental companies attempt to maximize their fleet utilization (and profit margin) by booking as many cars as possible. For some companies, that means overbooking rentals, on the assumption that some people won't show up to claim their reserved cars. However, despite what Strauss was told in San Francisco, Hertz does not knowingly overbook reservations, according to Hertz representative Paula Rivera.

"When customers make a reservation, they have every right to expect to receive the reserved vehicle at the time requested," says Rivera. "The fact that Mr. Strauss was advised that it would be a five-hour wait for the reserved car is unacceptable."

Most rental cars can be booked without penalty for no-shows, rendering fleet management more complicated. Factor in anything out of the ordinary—a large convention, a blizzard, a major sporting event—and you end up with dispirited travelers sitting on their suitcases in the rental car office. Hertz does move cars to help fulfill demand during special events, and each location takes inventory of available vehicles and reports it to the reservation center.

"Unfortunately, sometimes external factors prohibit this from being an exact science," says Rivera. "Periodically, customers will not return cars as expected, inclement/unpredictable weather may impact fleet availability and other factors may cause shortages."

In this case, Intel convention attendees had a hold on many Hertz cars, leaving Strauss out of luck. And although Strauss didn't like the answer, the San Francisco employee was correct that Hertz does not notify customers with reservations when no cars are available.

"It is not our normal procedure to call customers, as in most instances we would not know until the day of arrival about any issues and, at that point, for most people it would be too late," says Rivera.

But that doesn't mean customers should be left in the lurch. Car-rental companies could offer to pay for a taxi to a customer's hotel and back to the car location later, when a vehicle is available. Or help book a car through a competitor, with the original car-rental company paying the difference if the price is higher.