He returned to the Nationwide Series full-time for Penske in 2013 to drive the No. 12, now a Ford Mustang after Penske changed manufacturers. Hornish's 2013 season was his best to date, with 16 top-five and 25 top-ten finishes. At the season-opening DRIVE4COPD 300 at Daytona International Speedway, Hornish started and finished second despite his involvement in a serious crash on the final lap. Since race winner Tony Stewart was only eligible to score points for the Sprint Cup Series, Hornish was the series points leader after the Daytona race. At the Sam's Town 300 at Las Vegas Motor Speedway, he led for 114 laps in his second Nationwide victory. Before the season-ending Ford EcoBoost 300 at Homestead-Miami Speedway Hornish was second in points, eight behind Austin Dillon. Hornish qualified in the pole position and led for 37 laps, finishing eighth; Dillon, who finished twelfth, won the series championship. Hornish was second in the final point standings, with 1,177. During the season, car owner Roger Penske said that Hornish (who had driven for the team since 2004) would be released due to a lack of sponsorship. Hornish planned to drive Penske's No. 12 in the Sprint Cup Series at Kansas and Talladega. At Kansas he started in fourth place, running as high as third before crashing on lap 183 due to winds. The qualifier was rained out at Talladega, and Hornish failed to qualify because he had only one other Cup start that season.