Twenty years from now, when gasoline-powered cars are only used in parades and period pieces, announcements like the one Tesla trumpeted on Friday — “Tesla drivers just passed 3 billion electric miles, saving the world 120M gallons of gas 🙌” — might seem a little twee. But today, it’s big news.

And while three billion came very fast, four billion is going to come even sooner. The company marked one billion miles in June 2015 and passed the two billion mile mark in April, showing that the prevalence of the electric car company on the road is growing exponentially. If you consider the fact that the Tesla Model S didn’t reach a billion road miles until 2015, or about three years after the car debuted, the growth in the past year seems pretty staggering.

The recent growth is in line with an increase in sales. Earlier this month Tesla announced that it had sold over 24,500 vehicles in the past three months — a record number for the company for per quarter sales. In June, Tesla re-released a cheaper model of the Model S, making the car even more accessible to buyers less willing to spend nearly 70 grand on a new car.

Given these numbers, it’s hard to ignore the potential the release of the Model 3 will have on gas usage nationally. Within the first 24 hours of the Model 3 pre-order this April, the company sold 180,000 cars. With the pre-order maxing out at almost 400,000 orders, the number of electric miles driven is going to sky-rocket after the car is released in late 2017.

While it’s unclear how exactly Tesla calculated the number of gallons of gas saved, it’s indisputable that an increased number of electric cars on the road is good for the environment. The EPA estimates that the average gas-powered passenger vehicle emits about 411 grams of CO2 per mile. A Tesla vehicle, on the other hand, emits no greenhouse gases. That isn’t to say the cars come without their own environmental footprint resulting from factors such as production and sourcing of metals. But this new milestone is a start toward Tesla CEO Elon Musk’s master plan of “accelerating the advent of sustainable energy, so that we can imagine far into the future and life is still good.”

We asked Tesla about its math for this impressive stat and will update our story when we hear back.

Photos via Getty Images / Sean Gallup