Federal regulators are investigating Ford’s Mustang Mach E BlueCruise hands-free system after reports of two fatal crashes in which a Mach E hit stopped vehicles.

The National Highway Traffic Safety Administration says it determined in its initial investigation that BlueCruise had been engaged before each accident, both of which happened after dark.

BlueCruise, which NHTSA says Ford introduced in its 2021 model year for use only on certain roads, is available on other Ford and Lincoln vehicles. But the agency’s investigation involves the accidents involving Mach Es, and it’s reviewing the system in the 2021 to 2024 models.

Meanwhile, NHTSA completed an investigation of accidents involving Teslas equipped with the hands-free Autopilot system, finding that the technology did an insufficient job of ensuring drivers paid attention to the road and used the system appropriately while also instilling driver confidence with its “high control authority” and easy system engagement.

NHTSA says those dynamics were at play in 467 crashes involving Teslas through Aug. 30 of last year in which it found driver disengagement, including when Teslas left the roadway in “low traction conditions” contrary to Tesla’s own recommendations.

The investigation showed Autopilot’s “weak driver engagement system was not appropriate for Autopilot’s permissive operating capabilities,” resulting in a “critical safety gap,” NHTSA said in its report.

“This gap led to foreseeable misuse and avoidable crashes,” it said.

The agency closed the investigation since Tesla has recalled vehicles equipped with Autopilot, but the agency opened a review of the recall to determine its effectiveness.

DIG DEEPER: Small SUVs Not the Best on Some Crash Avoidance