Elon Musk says the Tesla Model S is the first EV to get a 400-mile range rated by the EPA. Here's how the company did it.

• The Tesla Model S Long Range Plus achieved an EPA-rated 402-mile range on a single charge, according to a company blog post.
• To achieve this, Tesla reduced the car's weight and maximized regenerative braking.
• Last month, Elon Musk claimed the EPA's original 391-mile range rating was the result of improper testing.

Range, it seems, is a big deciding factor for folks when it comes to picking the right electric vehicle. On Monday, Tesla announced that it had achieved "the first 400-mile electric vehicle" with the Tesla Model S Long Range Plus.

The company published a blog post, reporting that "starting today," all North American Model S Long Range Plus cars have "an official EPA-rated range of 402 miles." This marks a roughly 20% increase in range when you compare it to a 2019 Tesla Model S 100D with the same battery pack design.

The company achieved this through a number of methods.

First, it cut down on the weight of the car. Through designing and building the smaller Model 3 and Model Y, Tesla learned where it could trim weight while simultaneously keeping the "premium feel and performance" of both cars. The in-house seat manufacturing was standardized and the battery pack and drive units were made with lighter-weight materials as well.

The new, 8.5-inch-wide wheels work to reduce aerodynamic drag more than the ones on the previous Model S Long Range did. And when used with a low rolling-resistance tire, the wheels add a 2% improvement to overall range.

Further improvements include upping the efficiency of the drive unit — replacing the mechanical oil pump with an electric one — and maximizing regenerative braking.

What's neat about this whole thing, as Jalopnik pointed out on Monday, is that you don't have to wait for the 400-mile Tesla Model S Long Range Plus to come out; it's a car you can buy for yourself right now.

The Model S Long Range Plus's range has been a source of disagreement between the EPA and Tesla CEO Elon Musk. Earlier this year, the agency gave the Model S Long Range Plus a 391-mile range estimate instead of the 400-mile range estimate that Musk insisted the car could produce.

During a Tesla Q1 investor call last month, Musk, according to Roadshow, accused the agency of improper testing and claimed that someone there had left the keys in the car and the door open overnight. Because of that, the car apparently went into "waiting for driver" mode, and that drained 2% of its range, which led to the under-400-mile range estimate.

The EPA refuted Musk's claims and told Roadshow that it "conducted the testing properly."

At the time of Tuesday's writing, however, the FuelEconomy.gov site does not appear to list the Model S Long Range Plus's range figure. Yet, according to Autoblog, the site didn't list the car's previous 391-mile range, either.