The Tesla Model S Long Range Plus has officially received a 402-mile range rating from the Environmental Protection Agency, according to the FuelEconomy.gov website.

The Model S Long Range Plus received a 391-mile rating from the EPA in April, but the test was flawed CEO Elon Musk said.

“It should be said that the real Model S range is 400 miles,” Musk said during the Q1 Earnings Call on April 29. “But when we did the last EPA test, unfortunately, the EPA left the car door open and the keys in the car.”

The Long Range Plus has around 5% more efficiency compared to the 2020 Long Range model. The Tesla team stated in a blog posting that mass reduction, new “Tempest” Aero Wheels and Tires, increased efficiency of the drive unit, and regenerative braking improvements contributed to the Model S Long Range’s increased driving distance.

Tesla Model S Long Range Plus vs. Long Range comparison (Credit: fueleconomy.gov)

The Model S Long Range Plus utilizes a 100 kWh battery pack to power its extended travel capabilities. However, the car isn’t just suitable for long trips; it also packs a punch. With a 155 MPH and 0-60 time of 3.7 seconds, the Model S Long Range Plus will also satisfy the speed needs of anyone who requires an extra thrill.

While Musk was right about the real range capabilities of the Model S Long Range, the accomplishment is a testament to Tesla’s battery tech developments that have been a primary focus of the electric automaker for years.

Tesla has worked toward developing its own high-tech battery cells to achieve long-lasting and affordable packs for its vehicles and energy storage systems. After working with Jeff Dahn and his team of battery researchers and acquiring companies like Maxwell Technologies and Hibar Systems, Tesla made significant strides toward developing in-house cells that will revolutionize electric mobility.

The company plans to outline its new battery developments and technology discoveries at its “Battery Day” in September.

Tesla continues to push toward the improvement of its battery packs by utilizing different electrolyte solutions and electrode makeups. The company continues to submit patents that describe advances in the efficiency and performance of its battery packs.

Another focus of Tesla’s battery developments is eliminating the use of cobalt from its cells. Cobalt is effective in maintaining cycle stability in lithium-ion cells, but it is controversial due to its mining and labor practices. Tesla utilizes a series of third-party due diligence measures to ensure that the cobalt used in its batteries is responsibly sourced.

Although cobalt will eventually be removed from Tesla’s batteries, the company did sign a multi-year deal with Swiss-based Glencore to fulfill its needs for the mineral at Giga Berlin and Giga Shanghai.

The inclusion of the 402-mile range rating on the FuelEconomy.gov website is symbolic of Tesla’s sizeable lead in battery tech and efficiency. The company continues to improve the range of its vehicles through cell developments and software updates, and “Battery Day” will likely reveal what Tesla has been working toward behind the scenes for its “Roadrunner” project.

Tesla Model S gets official 402-mile EPA rating