By the 2025 model year, nearly all new vehicles sold in the U.S. will come with electronic alerts to remind people to not leave children behind in the back seats. Twenty automakers representing 98% of new vehicles sold have agreed to install reminders in an effort to stop heatstroke deaths. So far this year 39 children have died in the U.S. after being left alone in cars during hot weather. The advocacy group Kids and Cars says a record 54 children were killed last year.