U.S. safety regulators investigate Tesla's autopilot recall

The National Highway Traffic Safety Administration is investigating whether Tesla did enough to improve driver safety after recalling roughly 2 million vehicles to fix a software defect in their autopilot monitoring system.

Why it matters: This is just the latest hurdle Tesla has faced over safety concerns related to its autopilot software. NHTSA has been investigating the company's autopilot system and crashes for years.

Driving the news: The original recall, issued last December, covered almost all of the cars Tesla had sold in the U.S. at the time.

It was...