A tweet from Elon Musk indicating that Tesla might allow some owners who are testing a “Full Self-Driving” system to disable an alert that reminds them to keep their hands on the steering wheel has drawn attention from U.S. safety regulators.

The National Highway Traffic Safety Administration says it asked Tesla for more information about the tweet. Last week, the agency said the issue is now part of a broader investigation into at least 14 Teslas that have crashed into emergency vehicles while using the Autopilot driver assist system…

Philip Koopman, a professor of electrical and computer engineering at Carnegie Mellon University, argued that Tesla is contradicting itself in a way that could confuse drivers. “They’re trying to make customers happy by taking their hands off the wheel, even while the (owners) manual says ‘don’t do that.’ ”