One of the heirs of the vast Barilla pasta empire, Barilla started racing in 1975 and won the Italian 100cc karting title in 1976. In 1980 he entered Formula Fiat Abarth, and entered Formula 3 in 1981, where he won some races and finished third in the Italian Championship. He entered Formula 2 in 1982 with Minardi, but between 1983 and 1988 he concentrated in sports car racing.
Barilla first came to international prominence in 1983 with a privately entered Lancia LC2. After some excellent performances he was invited to join the works team the following season, taking second place at Kyalami, third at Monza and the Nurburgring and fourth at Silverstone.
Switching to the Joest Porsche team, he drove immaculately to win the 1985 Le Mans 24 Hours (with Ludwig and Winter) and the 1986 Mount Fuji 1000 Km (with Ghinzani). However, Paolo still yearned for success in single-seaters and spent two largely unproductive seasons in F3000 in Japan switching from team to team in search of a winning formula.
His friendship with Giancarlo Minardi provided him with the long-sought opportunity to race in Formula 1 and he began testing for Minardi F1. He did a substitution for Pierluigi Martini at Suzuka that year and afterwards signed to drive for the team in 1990. However his performances in the Minardi were disappointing and he was replaced by Gianni Morbidelli before the 1990 season was out.