Hybrid electric vehicles (HEVs) are gaining popularity but their fuel economy and environmental benefits are not yet enough to win over price-conscious buyers in the key United States market, industry officials said on Sept. 11, according to a Reuters report. HEV models from Honda Motor Co. and Toyota Motor Corp., which use both a conventional engine and an electric motor, are becoming more common in the United States and could take off soon in Europe, according to U.S. executives at a four-day European lead battery conference in Rome. In the United States, HEVs cost around $4,000 more than equivalent standard models. As fuel in the United States is much cheaper than in Europe, U.S. consumers feel little pressure to switch to HEVs, although the situation might change if fuel costs soared, delegates said.