Tesla's got to be gloating right now.

The electric automaker's crash rate has fallen ever since it launched its semi-autonomous Autopilot feature. The US National Highway Traffic Safety Administration (NHTSA) announced Thursday that it's finished a preliminary investigation into Autopilot and found no defects in design or performance, and according to the report, vehicle crash rates have dropped by almost 40 per cent.

Government regulators reviewed mileage and airbag deployment data from 2014 to 2016 for Model S cars and Model X vehicles equipped with Autopilot - either installed when the car was bought or through an update - and it officially concluded that systems like Autopilot help in reducing auto accidents. However, they warned that these systems do not mean drivers can stop paying attention to the road.

“While ADAS technologies are continually improving in performance in larger percentages of crash types, a driver should never wait for automatic braking to occur when a collision threat is perceived,” the NHTSA said. Keep in mind the government's probe began last summer after a controversial fatal crash in Williston, Florida that involved a Tesla with the Autopilot feature engaged.

Tesla has responded to the conclusions with the following statement: "At Tesla, the safety of our customers comes first, and we appreciate the thoroughness of NHTSA's report and its conclusion." CEO Elon Musk also tweeted and retweeted highlights from the report.