New research estimates autonomous miles based on previous data releases.

Tesla customers have driven over 1.2 billion miles (1.9b kilometre) with the company's semi-autonomous Autopilot systems engaged, a new report says.

First covered by Electrek, a team from MIT Human-Centered AI has produced (and is still updating a report) estimating the distance covered by Tesla vehicles operating with Autopilot turned on.

The report currently estimates that some 1.9 billion kilometres have been covered with the system engaged – more distance has been driven with the system in 'Shadow Mode', where Autopilot runs in the background without having any input on driving.

For both measurements, the MIT team has plotted the figures based on the handful of instances where Tesla has officially released its self-driving data.

The news comes after Tesla CEO, Elon Musk, tweeted 'full self-driving features' will be rolled out across the company's Autopilot-equipped models from August as part of its 'V9' software update, though he neglected to mention exactly what functions will be available.

"To date, Autopilot resources have rightly focused entirely on safety," Musk tweeted. "With V9, we will begin to enable full self-driving features."

While Tesla has covered nearly 2 billion kilometres with its semi-autonomous driver assistance systems, it's worth noting that its vehicles are currently limited to Level 2 driverless standards, which refers to features such as basic lane-keeping autonomous steering in combination with active cruise control.

There's been a few incidents involving Autopilot recently, too, some fatal. One Model X owner was killed when his car smashed into a barrier in Mountain View, California, while another suffered a broken ankle when her Model S slammed into a stationary firetruck at around 100km/h.

In the UK, a driver lost his license for 18 months after being filmed sitting in the passenger seat at around 65km/h, letting Autopilot do the driving.