Tesla’s fleet keeps racking up mileage. Back in October, we reported on Tesla reaching the 3 billion electric mile milestone and the company’s global fleet has managed to add 500 million in less than 3 months – bringing the total to 3.5 billion in December.

Over the weekend, the fleet reached another milestone on “the Road to the Next Billion”: 4 billion miles.

The company has been keeping track of its fleet mileage with a counter on the ‘Electric Road Trip‘ webpage.

Deliveries have been somewhat down and now flat on a quarter-to-quarter basis over the past 2 and the current quarter. Therefore, the fleet is not accelerating as quickly as it used to, but the company is expected to have passed the 200,000 vehicles mark between the Model S and X this quarter.

It’s about 100x bigger than its Roadster fleet.

Last year, Tesla CTO JB Straubel highlighted how quickly the company is adding electric miles by comparing the Roadster fleet with the Model S/X fleet:

A similar situation is expected to happen with the Model 3, which should in turn eclipse the Model S/X fleet.

As we recently reported, Tesla could deliver 80,000 Model 3 sedans by the end of the year under a perfect execution, which is unlikely. If everything goes as planned, Tesla’s Model 3 fleet could surpass the Model S/X fleet in volume at some point in 2018, less than a year after its launch – not unlike the Model S versus the Roadster.

When do you think the Model 3 will surpass the Model S/X both in number of units and in miles driven? Let us know in the comment section below.