A new report estimates that the company led by Elon Musk accounted for just under half of all battery-powered vehicles sold in the second quarter of the year.

The company’s share of U.S. electric vehicle sales by quarter

Tesla’s once-commanding share of the market for electric vehicles in the United States slipped below 50 percent in the second quarter of the year even as sales of battery-powered cars surged to a record, according to new estimates published Tuesday by a research firm.

Tesla accounted for 49.7 percent of electric vehicles sales from April through June, down from 59.3 percent a year earlier as the company led by Elon Musk lost ground to General Motors, Ford Motor, Hyundai and Kia, the research firm, Cox Automotive said. It was the first time the company’s market share fell below 50 percent in a quarter, according to Cox. The firm, a leading auto industry researcher, estimates market share based on registrations, company reports and other data.

The numbers are the latest sign that Tesla is losing its dominance in a market it in effect created in 2012 when it introduced the Model S sedan. Before that car, very few electric vehicles were sold in the United States.

Overall, U.S. electric vehicle sales climbed 11.3 percent from a year earlier, suggesting that consumer demand for the technology remains healthy even if sales are no longer growing at more than 40 percent a year as they were last year. Americans bought or leased more than 330,000 electric cars and light trucks during the quarter, accounting for 8 percent of all new cars sold or leased in the three-month period. A year earlier, electric vehicles accounted for 7.2 percent of the market, Cox said.

A few years ago Tesla didn’t have many competitors, and pretty much no other company could match its cars’ driving range on a full charge or acceleration. But established carmakers have been introducing electric vehicles that can travel 300 miles or more, equaling and sometimes exceeding the capabilities of Tesla’s cars.

There are well over 100 electric models available in the United States, according to a separate report published Tuesday by the Alliance for Automotive Innovation, an industry group. Prices have fallen as the supply and variety of models have increased, making it possible for more people to afford one.

Intense competition “is leading to continued price pressure, helping push E.V. adoption slowly higher,” Stephanie Valdez Streaty, director of industry insights at Cox, said in a statement.

Many consumers are now buying electric cars from established carmakers like BMW or Ford, which have large dealer networks that can provide maintenance and repairs. Tesla sells cars online and many consumers have said that it can be hard to get their cars repaired at the company’s relatively small network of service centers.

Tesla sales have also suffered from an aging lineup. Its best-selling vehicle, the Model Y, went on sale in 2020, making it dated by industry standards. Hyundai and its sister company, Kia, offer more electric models than Tesla, with competitive prices and newer designs.

ImageTesla’s share of the electric vehicle market in the United States fell below 50 percent in the second quarter for the first time since E.V.s have been sold in large numbers.Credit…Lauren Justice for The New York Times

After a slow start in the last couple of years, G.M. has recently begun rolling out vehicles designed to be electric, rather than models converted from gasoline cars. The company is also now using batteries made in the United States in a joint venture with LG Energy Solution. In a few months, G.M. is expected to start selling an electric version of G.M.’s Chevrolet Equinox sport utility vehicle for around $35,000 before taking into account a $7,500 federal tax credit.

Tesla said last week that its global sales fell 4.8 percent, to around 444,000, in the second quarter from the period a year ago. The company does not break out its sales by country, but Cox estimates that Tesla’s U.S. sales fell 6.3 percent in the second quarter, to 164,000 cars.

Mr. Musk may have also hurt Tesla sales with his embrace of right-wing politics on X, the social media platform he owns. Electric vehicle owners tend to be liberal or left-leaning and electric vehicle sales are highest in states that generally elect Democrats for statewide and federal offices.

In recent quarters, sales of electric vehicles have not grown as fast as some automakers had expected, but the market is still expanding faster than the one for gasoline vehicles. The market for hybrid vehicles has lately been growing even faster than for fully electric vehicles; hybrids, which do not have to be plugged in, allow consumers to avoid a patchy national public charging network.

Not all carmakers are benefiting. Electric models including Mercedes-Benz, Polestar, Porsche and Volvo fell in the second quarter from a year earlier, Cox said. The firm said it would publish detailed sales and market share figures on Thursday.