The U.S.’ top automotive safety regulator is notching up its investigation into the performance of Tesla’s Full Self-Driving (Supervised) driving software in low-visibility conditions. The National Highway Traffic Safety Administration’s Office of Defects Investigation (ODI) said on Thursday that it has upgraded the probe it launched in October 2024 to what’s known as an “engineering analysis,” its highest level of scrutiny. It’s a step that is often required before the agency tells a company to issue a recall. This is one of two investigations that ODI is running on Tesla’s Full Self-Driving (Supervised) software. The regulator is also probing more than 80 instances in which Tesla’s driver-assistance software has violated basic traffic safety laws, like running red lights. The investigations come as Tesla has spent months trying to get a robotaxi service off the ground in Austin, Texas.…