The National Highway Traffic Safety Administration said Friday it is in contact about a new Tesla driver assistance mode dubbed "Mad Max" that operates at higher speeds than other versions.

Some drivers on social media report that Tesla vehicles using the more aggressive version of its Full Self-Driving system could operate above posted speed limits.

NHTSA earlier this month opened an investigation into 2.9 million Tesla vehicles equipped with its FSD system over more than 50 reports of traffic-safety violations and a series of crashes.