Elon Musk is now making claims that Tesla is developing a cell with a range of 621 miles — months after failing to produce a million-mile battery.

The tech mogul made the reveal during a European Battery Conference saying Tesla’s ‘longest-range vehicles have over 327 miles of range and there’s more we could actually do.’

“We even have some under development long term that could do 600 miles,” he said.

The billionaire also hinted at a smaller Tesla hatchback specifically for the European market.

“In the US the cars tend to be bigger… I was driving a Model X around Berlin and we had quite a lot of trouble finding a parking space that could fit it,” Musk said during the interview.

On September 22, Musk took the stage for Tesla’s live-streamed Battery Day to reveal the firm is producing a cell, dubbed 4680, at its pilot Fremont gigafactory that will reduce cost and lower the sales price of its electric vehicles closer to gasoline-powered cars.

However, on looking investors expected not only to see a working battery but to also hear the news that it provides drivers with a one million mile range.

After the event, the angry investors slashed $50 billion from Tesla’s market value.

The Tesla CEO seems to have put the failed Battery Day behind him and is moving forward to eventually hold up to his promise of the million-mile battery – one-step at a time.

Musk mentioned that the new tabless battery, 4680, will be used in the Tesla Semi, saying such ranges are achievable for an electric semi-truck at ‘around 300 Wh/kg.’

“Getting a range of let’s say 500 km is I think quite easy, trivial to be frank, for a semi-truck and this is assuming a truck that is pulling a load of 40 metric tons,” Musk said. “If you want, for long-range trucking, you can take the range up to, we think, easily 800 km, and we see a path overtime to 1,000 km range for a heavy-duty truck.”

In addition, to bring down the cost of batteries, factories would have to produce massive amounts of cells.

Musk is now planning on building ‘the world’s largest’ battery-cell factory near its electric car plant in Berlin to achieve this.

Musk said battery cell production at the same German site would start with a capacity of around 100-gigawatt hours a year, before ramping up to 250 GWh per year.

At that point, Musk said he was ‘pretty confident it’d be the largest battery-cell plant in the world’.