Electric models from the luxury car brand have been very successful, but they may struggle once a $7,500 federal tax credit ends next month.

© Brett Carlsen for The New York Times

Electric models from the luxury car brand have been very successful, but they may struggle once a $7,500 federal tax credit ends next month.

The Commerce Department plans to impose a 93.5 percent levy on Chinese graphite, an essential ingredient in the batteries that power electric vehicles.

The company has devoted resources to autonomous driving rather than developing new models to attract car buyers.

China’s lead in electric vehicle technology, which is already huge, could become insurmountable if incentive programs are slashed, auto experts and environmentalists say.