1985 proved to be a historic year for Spencer. He began the season by winning the prestigious season opening Daytona 200. Spencer also won the Formula 1 and 250cc classes, making him the only rider to win all three divisions in a single year. Spencer also competed in both the 250cc and 500cc Grand Prix World Championships, winning both titles in the same year. That made him the fifth (and last) rider ever to win in the 500cc and the next class down and, due to class changes, the only rider to win in both 500cc and 250cc in one year. His career was cut short by wrist injuries that some believe were caused by the physical strain of competing in two championships during a single season.