A major player in the "mighty midgets" at Los Angeles's Gilmore Speedway in the late 1940s, McGrath won the first CRA (California Roadster Association) championship in 1946 and was dubbed "King of the Hot Rods".

His efforts, along with those of friend and teammate Manuel Ayulo, helped establish track roadsters as viable race cars.

McGrath's storied 26-lap duel with Bill Vukovich in the ill-fated 1955 Indianapolis 500 ended when the magneto on his Hinckle Special Kurtis 500C's Offenhauser (Meyer-Drake) engine failed on lap 54.

Fellow Californian and two-time Indy winner Vukovich died three laps later in a chain-reaction crash while in the lead.

Drivers competing at Indy during those years were credited with World Championship points and participation.