There's an electric car you can buy, right now, that has more than 400 miles of range — which is what you'd expect from an average gas car.

On Monday, Tesla announced that the North American variant of its Tesla Model S Long Range Plus car has an official, EPA-rated range of 402 miles, making it the first widely available electric car with a range of more than 400 miles.

According to Tesla, this is a nearly 20 percent increase in range compared to last year's Model S 100D which has a same battery pack design. So how did Tesla's engineers manage to push the range to 402 miles? Little by little.

Some of the improvements Tesla has made to the car include mass reduction, new aerodynamically optimized wheels and tires, increased drive unit efficiency (which includes a new electric oil pump and an improved gearbox), and improvements to regenerative braking.

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Tesla started implementing these changes when it began manufacturing the Model S Long Range Plus in its Fremont factory. Company CEO Elon Musk says that all Model S Long Range Plus cars manufactured after late Jan. 2020 will receive the new 402-mile rating.

With this achievement, Tesla beat Rivian's upcoming RT1 truck to the punch, as that car should be available with a 400-mile range, but the car isn't yet obtainable and the figure has not yet been certified by EPA.

Tesla also point out the improvements it has done to its Supercharger network, which now numbers 17,000 units in the U.S. This doesn't directly increase an individual car's range, but it helps reduce range anxiety.

There's a bonus for potential buyers: Tesla has also recently reduced the price of the Model S Long Range Plus, so you can get the electric car with the biggest range for $5,000 less.