San Francisco, Aug 19 : Elon Musk-run Tesla has come under heavy scrutiny on the controversial Autopilot advanced driver assistance system that has allegedly killed many, with both federal and state regulators turning up the heat on electric car-maker. The National Highway Traffic Safety Administration (NHTSA) has upgraded its investigation from a preliminary evaluation to an engineering analysis, asking Tesla to answer questions about its cabin camera as part of a probe into 830,000 Tesla vehicles that include Autopilot. "Describe the role that the cabin camera plays in the enforcement of driver engagement/attentiveness and the manner in which its inputs are factored into the subject system's operation," the US regulator said in a letter to Tesla late on Thursday. The letter asked Tesla to share inputs on the impact on driver engagement alert types and timing and how it integrates with the existing engagement strategy; recoverable data elements pointing to its influence either via telemetry or from the vehicle's onboard storage; and impact on driver alerting and recoverable data if the driver does not opt to share data from the camera with Tesla. According to Tesla, the cabin camera can determine driver inattentiveness and provide them with audible alerts, to remind them to keep eyes on the road when Autopilot is engaged. Tesla introduced its camera-based driver monitoring system in May last year. The NHTSA is investigating at least 16 crashes in which Tesla owners were potentially engaging Autopilot and then crashed into stationary emergency vehicles, resulting in 15 injuries and one fatality. "Describe in detail the engineering and safety explanation and evidence for design decisions regarding enforcement of driver engagement/attentiveness during the subject system's operation in the subject vehicles," said the US transportation agency. Earlier this month, the Department of Motor Vehicles (DMV) in California accused Musk-run Tesla of running fake claims about its Autopilot and Full Self-Driving (FSD) features. The agency said in its filing that Tesla "wrongly implies" that cars equipped with the technology can operate autonomously. Tesla has now responded, asking the California DMV for a hearing to present a defense against the claims that it misled prospective customers, reports TechCrunch. The California DMV filed two separate complaints, alleging Tesla made "untrue or misleading" claims about its vehicles' autonomous driving capabilities. Former US presidential candidate Ralph Nader has called Tesla's FSD technology as one of the "most dangerous and irresponsible actions" by a car company in decades. /IANS