Ryan Hunter-Reay will use No. 1 this season to recognize his reign as IndyCar champion.
Hunter-Reay had been using the No. 28 in honor of the 28 million people living with cancer worldwide.
But switching to No. 1 is somewhat customary for the defending champion in open-wheel racing, although Hunter-Reay becomes the first IndyCar driver to make the change since Scott Dixon following his 2003 title.
Hunter-Reay says it was important to everyone at Andretti Autosport and its sponsors that they be recognized for their accomplishment.
It's not the only number change for the organization: Marco Andretti will start using No. 25 next year. He says he believes the No. 26 has been unlucky for him the last seven seasons.