July 24 (Reuters) - European car parts supplier Forvia lowered its sales and margin forecasts on Wednesday due to sluggish global auto demand and additional one-off costs in its North American car interior business.

Forvia expects its sales to be at the lower end of its guidance of between 27.5 billion and 28.5 billion euros ($29.8 billion and $30.9 billion) this year. Similarly, its operating margin should come at the bottom end of its 5.6% to 6.4% range.

The outlook is based on the estimated worldwide automotive production of 88.7 million vehicles this year, down 2% compared to 2023, Forvia said in an earnings statement.

"In the first half of the year, the automotive environment was characterized by broadly flat automotive production year-on-year and a slowdown of the pace of electrification in Europe," Forvia said, adding its half-year operating margin was hit by one-off extra costs in the interiors segment in North America due to a problem with a supplier.

Forvia, which supplies parts to Stellantis, Volkswagen and Ford, and is also active in China, is fighting to recover its margins as the automotive sector grapples with falling auto demand and competition from Chinese manufacturers. ($1 = 0.9219 euros) (Reporting by Nathan Vifflin; editing by Milla Nissi)