Germany's automaker BMW AG said on Friday it was the biggest U.S. automotive exporter by value for the fifth consecutive year, with exports totaling over $8.4 billion in 2018.

The company said it exported 234,689 units of its X model sport utility vehicles and coupes from its Spartanburg, South Carolina, plant during 2018.

"Despite...the ongoing uncertainty regarding trade and tariffs, plant Spartanburg is still positively contributing to the U.S. balance of trade," said Knudt Flor, president and CEO of BMW Manufacturing Co LLC.

BMW's U.S. export report comes at a time when U.S. President Donald Trump has threatened to saddle imported cars and auto parts with steep tariffs of up to 25 percent.

Automakers, however, warn that such tariff on imported cars and parts would add thousands of dollars to vehicle costs and potentially devastate the U.S. economy as auto companies cut jobs to maintain profits.

"The remarkable partnership between BMW and South Carolina continues to thrive, and this is evident by the fact that our state remains the nation's leader in the export sales of completed passenger vehicles," South Carolina Secretary of Commerce Bobby Hitt said.