DETROIT — Starting in September 2027, all new passenger vehicles in the U.S. will have to sound a warning if rear-seat passengers don’t buckle up.

The National Highway Traffic Safety Administration said Monday that it finalized the rule, which also requires enhanced warnings when front seat belts aren’t fastened.

In a statement, the agency estimated the new rule will save 50 lives per year and prevent 500 injuries when fully in effect.

The new rule will apply to passenger cars, trucks, buses except for school buses, and multipurpose vehicles weighing up to 10,000 pounds.

The rule also lengthens the duration of audio and visual warnings for the driver’s seat. — Associated Press