Hunter-Reay began to compete in the Rolex Grand-Am Sports Car Series in 2006 for SAMAX/Doncaster Racing in the #17 SAMAX/Doncaster Racing Porsche GT3 Cup in the GT class in three races. At both the U.S Sportscar Invitational at Mazda Raceway Laguna Seca and The GAINSCO Grand Prix at Phoenix International Raceway Hunter-Reay's co-driver was Ian James and the Rolex GT Series Challenge at Lime Rock Park with Mark Greenburg. At Laguna Seca the car started in 32nd place overall and in 4th place in class. The car completed 86 laps to finish in 23rd place overall and in 3rd place in its class. At Phoenix the car started in 26th place overall and in 3rd place in its class. The car retired after 91 laps to finish in 33rd place overall 12th place in its class. At Lime Rock the field consisted only of GT cars and Hunter-Reay started in 18th place and retired after 11 laps and finished in 18th place. Hunter-Reay then competed in the season-ending Discount Tire Sunchaser 1000K at Miller Motorsports Park for SunTrust Racing in the #10 SunTrust Banks Riley-Pontiac with Wayne Taylor and Max Angelelli in the DP class. The car started in 5th place both overall and in its class. The car completed 186 laps to finish in 14th place both overall and in its class. Hunter-Reay also finished 27th in the GT drivers standings with 107 points while the #17 SAMAX/Doncaster Racing entry finished 4th in the GT teams championship with 392 points. Hunter-Reay finished 97th in the DP driver's standings with 17 points while the #10 SunTrust Racing entry finished 3rd in the DP teams standings with 431 points.