Possible Clues:

• Onetime Dr Pepper rival
• Dr Pepper rival renamed in 2001
• Coke's answer to Dr Pepper
• It got some 'Xtra' flavor in 2001
• Coca-Cola offering from 1974 to 2001
• Dr Pepper alternative
• Dr Pepper rival, once
• Coca-Cola product
• Onetime Dr Pepper alternative
• Dr Pepper rival