Five or 10 years ago, about one-fourth of typical new-car buyers in the Dallas area were upside-down in the vehicles they traded in. Today, that number may exceed 75 percent, dealers say, according to the Seattle Times.

"It is an industry problem," said Don Herring, chairman of the New Car Dealers Association of Metropolitan Dallas and a Mitsubishi dealer in Dallas and Plano, Texas.

Longer-term loans and a soft used-car market are mostly to blame for the growth of negative equity, dealers said. The typical new-car loan now is for 60 months, which means consumers may make payments for 40 months before they will have any equity.

Moreover, the frenzy of new-vehicle buying last fall - ignited by zero percent financing - created a glut of trade-ins that pushed used-car values down. A year ago, most cars were depreciating at a rate of about 12 percent a year. In January, the rate was running close to 19 percent, according to Paul Taylor, chief economist of the National Automobile Dealers

Association (NADA).