Tesla Inc.’s grip on Europe’s electric-vehicle market continues to weaken, with UK registrations tumbling 60% year-on-year in July, according to national industry data. The slide deepens a slump that has seen sales in Germany and the UK fall by more than half and French registrations drop 27%, despite the US carmaker ramping up output of a refreshed Model Y after earlier production line changes. The slowdown is creating an opening for China’s BYD Co., whose registrations more than quadrupled in both Germany and the UK last month. BYD outsold Tesla in Germany for the third time this year and lifted its UK market share to 1.91%, just shy of Tesla’s 2.0%. Several analysts now forecast BYD will surpass Tesla in global battery-electric vehicle deliveries for the full year, underscoring the intensified competition facing Chief Executive Officer Elon Musk.