Tesla Model S inches closer to 400-mile range mark

New Tesla Model S owners are in for a lovely surprise. CEO Elon Musk took to Twitter this past Friday to confirm all of the electric sedans built in "recent months" feature a driving range upgrade. The new figure? An EPA-estimated 390 miles of range.

That's a 17-mile improvement over the previous Model S Long Range Plus variant, the most affordable version. Those eying a Model S Performance will still find the same 348-mile range attached to them.

The news came as a surprise after Musk commented during the automaker's fourth-quarter earnings call that the car would likely ring in around 380 miles of range. In a double surprise, he revealed  Tesla's been building the cars for at least a couple of months with the elevated range ratings. According to Musk's tweet, owners will have the extra range unlocked via a free software upgrade at some point.

Tesla didn't immediately respond to Roadshow's request for comment on when owners can expect the upgrade.

The Model X gets in on the upgrades, too. The Long Range Plus model now boasts an EPA-estimated 351 miles of range, up 23 miles. Like the Model S, it'll get a free software upgrade as well.

Tesla Model S Long Range takes us back to the future

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Notably, these updates come on the heels of Musk's comments declaring 400 miles of range is very much in reach. As for how Tesla's getting there, Musk explained on Twitter that numerous "hardware improvements" are the keys here. They've been implemented "gradually over the past several months," he added.

Should Tesla continue its advances, it may not be long before we do see an EV with 400 miles of range. Before then, Tesla does have fresh competition in the race to 400 miles, however. Lucid Motors plans to unveil its production Air electric sedan this April, and it should go 400 miles even at highway speeds.

Watch this: Tesla Model S Long Range pulls further ahead of the EV pack

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