Motorsports Kyle Busch died of pneumonia that progressed into sepsis: What we know By web-interns@dakdan.com - May 25, 2026 0 5 FacebookTwitterPinterestWhatsApp As the motorsports world resumed racing Saturday, May 23, the Busch family revealed what killed Kyle Busch: severe pneumonia that progressed into sepsis, claiming the two-time NASCAR Cup Series champion at 41.