The agency's only criticism is that Tesla's information about system limitations is "perhaps not as specific as it could be."

The National Highway Traffic Safety Administration appears to have vetted safety claims surrounding Tesla's Autopilot technology.After spending six months investigating the first fatal Autopilot crash, the agency's office of defects investigation identified no defects "in design or performance of the [automatic emergency braking] or Autopilot systems ... nor any incidents in which the systems did not perform as designed," according to the closing report (PDF).

The inquiry will undoubtedly be reviewed in detail by other automakers that are planning to launch advanced semi-autonomous systems and eventually fully autonomous vehicles. NHTSA investigators were not just looking at how a Model S failed to identify and brake for a semi-trailer across a Florida highway, but also how the company implemented the technology and warned users of its inherent limitations.

An ODI analysis of airbag deployment crashes in the Model S and Model X before and after Autosteer installation found that crash rates dropped by nearly 40 percent after Autosteer installation, reducing the crashes per million miles from 1.3 to 0.8.

The agency's only apparent criticism focuses on Tesla's instruction manuals, which allegedly provide limited information regarding the particular types of scenarios that interfere with proper operation of the emergency braking system.

"Although perhaps not as specific as it could be, Tesla has provided information about system limitations in the owner's manuals, user interface and associated warnings/alerts, as well as a driver monitoring system that is intended to aid the driver in remaining engaged in the driving task at all times," the agency concluded.

Tesla is viewed as one of the most aggressive automakers in rolling out such technologies, but the NHTSA did not conclude that the company brought its Autopilot technology to market too early or failed to implement tighter controls over how it is used. It is unclear if other automakers will take a less conservative approach in light of the NHTSA's conclusions.