SAN MATEO, Calif. -- According to the recent Keystone Customer Experience Ratings for Rental Car Web Sites study from Keystone Systems, reputation, price satisfaction, the online reservation process and the rental search process are the leading factors driving customers toward preferred rental possibilities, or "likelihood to rent."

Based on research with 2,000 online consumers, the study looked at how they interacted with 10 leading travel and rental car Web sites including Alamo, Avis, Budget, Dollar, Enterprise, Expedia, Hertz, Orbitz, Thrifty and Travelocity.

"As the online travel and online rental car industry matures the product offerings are gaining more variation and differentiation," said Dr. Bonny Brown, director of research at Keynote. "This differentiation in offerings appears to be having an effect on brand reputations which, as a result, are becoming increasingly important drivers of consumer booking and rental intent."

Though online travel agencies Orbitz, Travelocity and Expedia performed best overall, the rental car sites were tops in quality and reputation – an indication of possible growth in the online rental market.

Orbitz topped the rankings with online consumers noting brand perceptions, price satisfaction, rental car search process and overall site and design organization as its strong points. This was the first time any site has ranked ahead of Expedia.

Online travel agencies bested rental companies in terms of customer satisfaction. Rental car companies, however, outperformed the online travel agencies with consumer perceptions about the quality of cars the sites offer.

The biggest frustration of online consumers, across all sites, is uncertainty as to when their credit cards will be charged for the rental, with 20% reporting such uncertainty. More than half (55%) expect to be charged when they pick up the car, whereas just 20% expect to be charged at the point of making the reservation online.