July was a bad month for Tesla in Europe and a good one for BYD. It might signal that the tides are turning toward BYD as the top EV company in the world.

Tesla Inc.’s rough stretch in Europe continued as data from Germany and the U.K. showed the U.S.-based electric-vehicle maker’s sales were cut in half last month.

Tesla's new car sales plummeted in both Britain and Germany in July, according to industry data published Tuesday, extending a protracted European downturn for the U.S. electric automaker. Data published by the U.