Hyundai and Kia are losing buyers over their false mileage claims.

New data shows that overstated mileage claims made by Hyundai and Kia are turning some buyers off to the brands. The Korean automakers confessed in early November to inflating the mileage claims on about 40 percent of their lineups.

According to Edmunds.com, "purchase intent" for buyers interested in Hyundai and Kia vehicles has dropped significantly since the automakers admitted to artificially increasing the stated mileage of several of their vehicles. The "purchase intent" for Hyundai's Elantra compact - one of the vehicles falsely touted as a "40-mile-per-gallon" vehicle - declined from 6.7 percent in late October to 6.3 percent as of November 18. The Hyundai Veloster, Hyundai Accent and Kia Rio have suffered similar declines.

The Kia Soul has been the hardest hit by the false mileage claims. Following a 6mpg decrease in claimed highway mileage the Soul's "purchase intent" dropped form 9.2 percent to just 7.3 percent.

"In the U.S., Hyundai in particular has made a media and consumer 'talking point' of the number of 40-miles-per-gallon vehicles it sells and how well it sells those models, so this development has been considerably embarrassing," Bill Visnic, a senior editor at Edmunds.com, told Reuters.

Visnic added that "purchase intent" is highly correlated with actual vehicle purchases.

In addition to future sales, the false mileage claims are expected to cost the automakers' $100 million a year until all the vehicles involved are scrapped.