Tesla is releasing two new lower-cost versions of its all-electric Model S sedan. The new Model S 60 and 60D start at $66,000 and $71,000, respectively, and are already available on Tesla's website.

The new base version, the rear-wheel drive Model S 60, has a top speed of 130 miles per hour, can go from zero to 60 miles per hour in 5.5 seconds, and is capable of going 210 miles on a full charge, according to Tesla. The 60D is all-wheel drive, has a range of 218 miles, and does zero to 60 in 5.2 seconds.

Both new models will come equipped with the hardware for Autopilot, Tesla's self-driving technology, but buyers will still have to pay extra to enable the feature.

Tesla just overhauled the Model S line in April, giving the car a new front grille, new LED headlights, faster charging, and building in the option to include the air filtration system from the Model X (which Tesla calls the "Bioweapon Defense Mode"). The same will be the case with the new Model S 60 and 60D.

The numbers in Tesla's model names refer to the capacity of the battery — the Model S 90 has a 90 kWh battery, for example — and Tesla used to sell a Model S 60 until it was replaced by the 70D in 2015. The difference this time around is the car is actually equipped with a 75kWh battery, not just a 60kWh version.

This was another part of that April refresh. Tesla stopped making batteries with different capacities for its lowest-end models, instead opting to put a 75kWh version in all of those cars and limiting the capacity with software. As is the case with the Model S 70D, buyers of the new 60 and 60D will have the option of paying Tesla ($9,000, in this case) to unlock that extra capacity down the road.

This move, along with the other software updates Tesla offers, has started to change the way we buy (or think about buying) cars. But today's news also shows how valuable the approach is to Tesla — the company just created a more affordable version of its most popular car with just a few lines of code. And since the manufacturing cost is exactly the same, 60 and 60D buyers are essentially getting a great deal that’s being subsidized by buyers (and upgraders) of the 75kWh version.

Correction: This story mistakenly stated that the Bioweapon Defense Mode would come standard on the new models. The article has been changed to reflect that.

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