By George Polgar

PHILADELPHIA (CBS) – The storybook ride of Hyundai and Kia from off-brand import to serious competitive contender in the giant US automotive marketplace hit a major speed bump recently when the companies settled combined federal investigations by the Environmental Protection Agency and the Justice Department for overstating fuel-economy claims.

READ MORE: Philadelphia Commerce Director Michael Rashid Resigns After He Reportedly Made Anti-Semitic Remarks, Verbally Abused His Staff

Just five years ago, riding a quality transformation wave, South Korean car-making cousins Hyundai and Kia were the only major brands aside from Subaru to post sales increases amidst the auto market collapse.

READ MORE: Water Main Break Flooding Multiple Buildings In Society Hill Section, Officials Say

With a payment of $100 million, and $200 million in forfeited regulatory credits, this is the largest such fine on record and could set a precedent for other car companies which have been forced to roll back mileage claims. Notably Ford and BMW Mini have recently adjusted mileage claims under regulatory scrutiny.

This fine, on top of a $400 million class action civil settlement last year, has not only lightened the purse but significantly dinged the reputation of the Hyundai and Kia which made its 40 mpg rating central to its marketing campaigns.

MORE NEWS: Philadelphia Union Miss Out On Eastern Conference Championship Amid COVID Crisis

Dismal sales of the new version of Hyundai’s best selling Sonata spells more bad news!