He made 17 starts in the AAA Championship Car series from 1948 to 1952, capturing a victory in his rookie season at the Milwaukee Mile as well as winning the non-championship Indianapolis Sweepstakes at Williams Grove Speedway.

The newly built Darlington Raceway was also the first "Super Speedway" for NASCAR, even though it was a little under a mile and a half in size.

Mantz and his Plymouth were the race's slowest qualifier, almost 10 MPH slower than the pole winner, Curtis Turner.

He would win by 9 laps over the second-place finisher, Fireball Roberts, with an average speed of 75.250MPH.

[3] Mantz was also the first person to try to bring NASCAR sanctions to the West Coast of the United States.

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