Tesla Motors has unveiled a new battery pack for the performance versions of its Model S and X cars that will extend the range and mean faster acceleration.

Elon Musk, chief executive of the electric car maker, hailed the upgraded battery as a “profound milestone”.

He said the battery cell chemistry is the same, but the reconfigured product stored more energy in the same space.

Tesla, which this month posted a steeper-than-expected loss, is adding a new sedan car to its sports line-up.

Mr Musk claimed that the new 100-kilowatt hour battery pack means high-end versions of the Model S sedan, called the P100D, will be the world’s fastest accelerating car in production.

It will do 0-60mph in 2.5 seconds. He said there were faster cars on the market, but these were limited-run vehicles, while the Tesla is aimed at the mass market, he said.

“These are very profound milestones and I think will help convince people around the world that electric is the future,” he said on a conference call with journalists.

The new battery extends the range of performance versions of the new Model S well beyond 300 miles (482.8 km), from about 290 miles, Tesla said.

Mr Musk said that in cool weather, a driver could travel from San Francisco to Los Angeles – a nearly 400 mile drive – without recharging.