Sales of hybrids, not including plug-in hybrids, rose by 21 percent to just over 2 million, or nearly 30 percent of the market.
Sales of battery electric vehicles ticked 1.6 percent higher, to 954,094 units, or 13.9 percent of the market.
Petrol vehicles remained the biggest segment with a market share of 35.2 percent, but sales dipped 1.5 percent. Sales of diesel vehicles fell by 7.9 percent.
Sales of vehicles using fuel cells, natural gas, liquefied petroleum gas, super-ethanol and other fuels bounded 6.9 percent higher.
European carmakers have committed to shifting production to battery electric vehicles but have recently appeared disappointed by the lack of sales growth despite introducing more models.
The stall in consumer uptake comes as government incentives to purchase electric vehicles have dropped in some countries and while there are still few models affordable to those on modest incomes.
The ACEA said that while overall sales in the European car market expanded modestly in the first half of the year to nearly 6.9 million vehicles, they remain considerably lower than pre-pandemic levels.
Some 8.7 million vehicles were sold in Europe in the first half of 2018.