After winning the SCCA national Formula Atlantic championship in 1993, he moved up to the CART-sanctioned Toyota Atlantic series in 1994. In 1997 Greg Ray made his Indy Racing League debut driving for Thomas Knapp in an unsponsored black #97 car, but made his mark on the series a year later during qualifying for the Indianapolis 500. He qualified second behind A.J. Foyt's driver Billy Boat, again driving the same, plain, black #97 car that attracted sponsorship from local businesses and the national anti-tobacco compaign, known as Ash Kicker Racing. Though he failed to finish that race he scored several good results and caught the eye of successful businessman and team owner John Menard.
In 1999 he won the IRL championship on the strength of three victories. In 2000 he qualified on pole at Indianapolis but subsequently finished 33rd and last. It was a difficult season with only one victory, at Atlanta driving a newly-sponsored light and dark green Conseco car and by 2001 he and Menard had split. Jaques Lazier replaced him and won his first victory at the Chicagoland Speedway.
In 2003 he started his own team, Access Motorsports, with Panoz chassis and Honda engines. He gained sponsorship from TrimSpa but failed to light up the scoreboard and in 2004, he ran a few races before giving his seat to former Infiniti Pro Series champion Mark Taylor. The team closed at the end of the year from a lack of sponsorship.