Carpenter returned with ECR in 2013 to drive the No. 20 Dallara-Chevrolet. Carpenter improved his qualifying results on the ovals, with a worst start of 14th at the Pocono IndyCar 400 at Pocono Raceway. Despite this, Carpenter struggled away from the ovals, achieving a best start of 14th at the Itaipava São Paulo Indy 300, and a best finish of 13th in the opening race of the double-header in Toronto. On the ovals, Carpenter's results were significantly better, including pole position at the Indianapolis 500, where Carpenter's single-car team beat out all three cars fielded by Team Penske and all five cars fielded by Andretti Autosport, two of the largest teams in the series. In the race, Carpenter led for a race-high 37 laps, only to suffer handling issues in the second half of the race and dropped to a 10th-place finish. In the Firestone 550 at Texas, Carpenter qualified 9th and finished 4th. Carpenter's only disappointing oval race was the Milwaukee IndyFest at Milwaukee where Carpenter qualified 20th and finished 14th, two laps down. At the Iowa Corn Indy 250 at Iowa, Carpenter started and finished 4th after leading for 18 laps, being one of the few drivers to pose a threat to race winner James Hinchcliffe. Carpenter then finished 9th at Pocono, where the Chevrolet engines lacked the fuel economy of the rival Honda engines. Carpenter's next competitive race was at the season-ending MAVTV 500 IndyCar World Championships at Auto Club Speedway, where Carpenter started 7th and finished 2nd after leading for a single lap. Carpenter finished the season ranked 16th, with 333 points.