The National Highway Traffic Safety Administration unveiled the final version of the new regulation on Monday and called it the most significant safety rule in the past two decades.
Toyota issued a "Do Not Drive" advisory for thousands of older models in the U.S., warning that a faulty air bag inflator has the potential to explode and seriously injure drivers or passengers.
The recall comes after a two-year investigation by the National Highway Traffic Safety Administration into a series of crashes — some deadly — that happened while the Autopilot system was in use.
More than 1.6 million Hyundais and 1.7 million Kias are at risk of engine compartment fires. Owners of the affected vehicles are urged to park them outside and away from homes and buildings.
The proposal would increase fuel economy for cars by 2% annually — and twice as fast for trucks and SUVs. The rule would pair with the EPA's ambitious plan to promote electric vehicles.
Although the study authors say the results can't be used to gauge drug use on the roads nationwide, the high number of drivers, passengers and others with drugs in their systems is concerning.
