The Federal Trade Commission yesterday announced a $25,000 penalty against a District used car dealership that was sold six months ago.

This is the third case the FTC has brought under 1985 rules requiring dealers to display a window sticker, called a buyer's guide, explaining warranties on all used cars offered for sale.

The FTC charged G.B. Enterprises Inc., which operated Lee Used Ford Sales on Benning Road NE, with failing to display the stickers, failing to include required warranty information in sales contracts and illegally including a limitation on warranties and damages in its standard warranty agreement.

Although G.B. Enterprises submitted a certified check Jan. 12, when it signed a consent decree to settle the charges, the FTC did not announce the agreement until yesterday.

According to the FTC announcement, "The proposed consent decree prohibits G.B. Enterprises from violating the used car rule and the warranty disclosure rule in the future." The decree, filed yesterday in U.S. District Court for the District of Columbia, is subject to approval by the court.

The company's owners sold Lee Used Ford to Northeast Ford in December 1986, according to Christopher Smith, the attorney representing G.B. Enterprises in the FTC action. Smith said he unsuccessfully argued with the FTC that they should not pursue the case since his clients were leaving the business.