Dale Earnhardt Jr looks from the garage before practice at Daytona International Speedway in Daytona Beach, in February 2016. Associated Press/Wilfredo Lee CHARLOTTE, N.C. — Dale Earnhardt Jr. abruptly announced his retirement at the end of the season Tuesday, a decision that will cost NASCAR its most popular driver as the series scrambles to rebuild its fan base. Colorful, candid and talented, Earnhardt has been plagued by concussions the last several years and he missed half of last season recovering from the latest head injury.