Tight credit is hampering the purchase plans of most U.S. consumers in the market for a new vehicle, according to a study by Accenture, a management consultancy.

The survey of 504 consumers, first conducted in October and repeated in April indicates 64% had problems purchasing a car. Some 30% of new-car buyers were forced to downgrade and buy a less-preferred and less-expensive vehicle. For 34%, it meant holding off on the purchase altogether.

Among those who indicated tight credit prevented them from buying a vehicle, 91% said they were delaying their next automobile purchase until the economy improves.

“The troubled economy is taking a toll on car buying, but our survey suggests that a significant number of consumers are still seeking vehicle purchases.” says Richard Spitzer, managing director for Accenture Automotive and Industrial Equipment.”

The troubles would-be car buyers have seen lately may contain a core of good news to the auto industry. It suggests pent-up vehicle demand is building.

“As credit thaws, consumer confidence builds and dealer incentives take hold, the industry will have a more stable market, and most likely, pent-up demand to draw on for auto sales,” Spitzer says.

He adds: “The automotive industry will continue to face challenges. But, consumers will always be key to its success, and our survey reflects encouraging signs that they want to purchase vehicles and car buying will improve.”

The Accenture survey also found consumer attitudes toward fuel-efficient and green vehicles changing.

Fuel efficiency remains the top criterion for selecting a vehicle, but its importance is dropping. Thirty-eight percent of respondents in the April survey view it as the most important reason. That compares with 51% of respondents in the October polling.

Consumer interest in hybrid-electric vehicles appears to be waning. Seventeen percent compared with 22% of earlier respondents expect to buy a hybrid as their next car. Ninety-four percent of current respondents say they’d be willing to pay up to $30,000 for a hybrid.