In 1991, it raced in all seventeen events, scoring 3 wins, two with Rick Mears, and one with Emerson Fittipaldi, placed 4th and 5th at the season's end respectively.

The PC-20 was powered by an Ilmor-Chevrolet V8 265A turbo engine and it debuted at the 1991 Gold Coast IndyCar Grand Prix where it qualified 6th and 7th with Fittipaldi and Mears, respectively.

Another caution does not alter the result as Mears powered away again to his record-tying fourth Indianapolis 500 Victory,[3] tying A.J Foyt and Al Unser, Sr. During the rest of the season, the Penskes weren't able to compete with Michael Andretti dominance, who clinched the title with 8 season wins.

[4] Nevertheless, Fittipaldi won at Detroit, and Mears scored a win at Michigan 500, as confirmation of the PC-20's competitive form on long ovals.

It made its race debut in the Gold Coast, Australia, at the renamed Daikyo IndyCar Grand Prix where it finished first and second, driven by Fittipaldi and Mears, respectively.