Carmakers' embrace of "employee discount pricing" this summer helped their short-term bottom line, but it hurt their brands in the process, according to a report on Forbes magazine's website.

According to a survey by market researcher Branddimensions, consumers saw the 'sweetheart' terms from General Motors, Ford and, to a lesser extent, DaimlerChrysler as signs that their cars weren't good enough to stand on their own. The ultimate result of the promotion was the widening of an already-existing gap in perceived quality between Detroit's Big Three and their Japanese counterparts, the report said.

"People thought they were desperate to unload excess inventory," Bradley Silver, CEO of Branddimensions, told Forbes.

According to the report, Branddimesnions said sales by the Big Three tumbled in September after rising over the summer. Also falling were consumer scores for brand image, quality, credibility and perceived resale value, among other attributes.