Tarquini started racing at the age of seven in karts. His father owned a kart track in Giulianova and the young Tarquini was soon winning races.
In 1983, after attending the CSAI racing school at Vallelunga, he entered a limited programme of Formula 3 driving a Spreafico March-Toyota 803 in six rounds of the Italian Championship.
He did a couple more F3 races in 1984 with Coloni but then returned to karting, winning the World, European and Italian Championships.
In 1985 he moved into Formula 3000 finishing sixth in his first year. He also competed at Le Mans that year driving a Brun Porsche 956B with Larrauri and Sigala, and had a test drive with Benetton.
In 1986 he competed once again in the F3000 Championship but with little in the way of results.
A third season in F3000 in 1987 with First Racing also saw him make his F1 debut for Osella at the San Marino Grand Prix. It was the only time they ran a second car that year. He also drove in the WTCC, sharing a Beretta Brixia Motor Sport Alfa 75 Turbo with Rinaldo Drovandi.
He joined Coloni for 1988 and started 8 of the 16 races, often failing to qualify due to the other slow cars all being exempt from pre-qualifying. His best result was 8th in Canada. Tarquini signed to drive for the FIRST team, but when their car failed crash tests, he started 1989 without a ride but joined AGS after Philippe Streiff's career-ending testing crash. He came 6th in Mexico and often threatened to score points, running 4th at the Monaco Grand Prix and 6th at the United States Grand Prix.
He remained with the team until late 1991, by which time it was totally uncompetitive and on the verge of folding. He moved to Fondmetal, and showed pace for them, scoring a major upset in Belgium 1992 by outqualifying Ivan Capelli's Ferrari. Sadly, this team too soon folded, and barring a one-off for Tyrrell in 1995 his F1 career was over.
By this time he had switched to Touring Cars, winning the BTCC title in 1994 in an Alfa Romeo featuring barely-legal aerodynamic enhancements.
He started races in both the British and Italian Touring Car Championship in 1995, and was also in the BTCC for David Richards' Honda team in the late 1990s, taking 4 further victories, as well as racing in Germany's STW Cup and the Belgian Procar series, before switching to the ETCC with considerable success.
Partly due to his links with Fondmetal, he had been an occasional test driver for Tyrrell, and was drafted in to deputise for the indisposed Katayama at the Nurburgring in 1995, though his one-off F1 return was not a particularly distinguished one.
In 1996 Gabriele stepped up to the high-profile International Touring Car series as a works driver alongside the experienced Larini and Nannini in the Alfa 155 V6 Tl and scored a big win at Silverstone, but endured a thin time otherwise. So it was back to the Super Touring category in 1997, the Italian switching his allegiance to Honda taking 4 further victories in his three years with the team. He aslo raced in the Germany STW Cup and the Belgian Procar series, before switching to the European Touring Car Championship (ETCC) with considerable success, remaining as it became the World Touring Car Championship (WTCC) in 2005. At present he drives a SEAT León in the WTCC.