Car dealership group AutoNation reportedly has lowered its second-quarter earnings forecast, citing significant declines in sales of Ford and General Motors products.

According to Reuters, the Fort Lauderdale, Florida-based company said it now expects to earn between 34 cents and 35 cents per share in the period ended June 30, compared with an earlier view of 38 cents to 40 cents per share - AutoNation said it sees full-year earnings per share from continuing operations in a range of $US1.35 to $1.40 due to the "difficult new vehicle retail environment."

The company reportedly said its cost structure in the second quarter was targeted for vehicle sales volume levels that did not materialise, particularly in June - low volume combined with high inventories caused gross margins to fall in its new vehicle business.