LONDON—Nearly one in five vehicles sold in the European Union in the third quarter was an electrified model as sales continued to soar while fossil-fuel cars slumped, according to sales data released on Friday by a trade organization. The European Automobile Manufacturers’ Association, or ACEA, which represents major European car, truck, van, and bus makers, said that battery electric and plug-in hybrid model sales across the European Union made up just under 19 percent of all sales. Battery electric vehicle sales jumped nearly 57 percent to more than 212,000 units, while plug-in hybrid models rose nearly 43 percent to more than 197,000 units. This is a slower pace of growth than in 2020 when sales almost trebled from a low base. But it compares with a 35 percent drop in sales for petrol cars—which still are the biggest sellers and account for nearly 40 percent of overall sales—and a more …