All vehicles will have to be equipped with a sound or bell warning if rear passengers don't buckle up by September of 2027. That's according to new rules from the National Highway Traffic Safety Administration that were finalized on Monday. The new rules also require enhanced warnings when front seat belts aren't fastened by Sept. 2026 and will apply to cars, trucks, multipurpose vehicles weighing up to 10,000 pounds and all buses except for school buses.RELATED STORY | Fatalities in US road crashes declined last year, NHTSA saysPreviously, sound warnings were only required for the front seat belts. The NHTSA said these new seat belt rules will help prevent more than 500 injuries and 50 deaths each year. According to the agency's data, rear passengers consistently use seat belts at a lower rate than front passengers which results in 822 fatalities and over 11,000 injuries on average annually.