Takagi was heavily influenced by his father, a Touring car driver. In the early 1980s he began racing karts, competing in his first championship kart race in 1987. After winning several All Japan National Kart A2 series races, Takagi ended his kart racing career in 1991 and began racing Formula Toyota in 1992. In 1993, he began competing in All Japan Formula Three, finishing 10th in his rookie season.
Formula One competition
During his performance in a 1994 race he drew the attention of Satoru Nakajima, a well-known Japanese Formula One driver, whereupon he joined the Nakajima Racing team and competed in the Formula 3000. He was heavily involved in the team from 1995 until he was chosen as Tyrrell's Formula One test driver in 1997. He competed regularly for Tyrrell in 1998, finishing as the 6th Japanese Formula One driver by the end of the year. Takagi later competed on the Arrows Formula One team, and his European popularity was on the rise. However there were organizational and communication problems between Takagi and both teams, and he left Formula One in 1999.
Post Formula One career
In 2000, Takagi joined Nakajima Racing's Formula Nippon team, earning eight victories in ten races, the most dominant performance ever by a driver in the series. He later competed in CART (Champ Car) for the Walker Racing team in 2001 and 2002 finishing in a career-best 4th place in Houston, Texas. He transferred to IRL and joined Mo Nuun Racing, finishing 10th in 2003. In the same year, he competed in the Indianapolis 500, starting in 7th place and finishing in 5th, earning him the Bank One Rookie of the Year prize.
After another, largely disappointing season in the IRL, Takagi returned to Japan in 2005 to compete in Formula Nippon once again, taking part ownership of the Cerumo team and running one of their cars in his own name (Takagi Planning with CERUMO). Takagi also was one of the co-drivers of the #38 Toyota Supra Super GT car, claiming the series title along with Yuji Tachikawa.
- 1987 -- Finished 8th in Japanese A2 National Kart Series championship.
- 1988 -- Finished 4th in Japanese A2 National Kart Series championship.
- 1989 -- won the Japanese A2 National Kart Series championship.
- 1990 -- won the Japanese A2 National Kart Series championship.
- 1991 -- Finished 2nd in Japanese FA National Kart Series championship.
- 1992 -- Won two races in Formula Toyota.
- 1993 -- Finished 10th in his rookie season in Japanese Formula 3 championship.
- 1994 -- Finished 6th in Japanese Formula 3 championship.-- Spot participation in Japanese Formula 3000 championship from Nakajima Planning, scoring three top-10 finishes.
- 1995 -- Finished 2nd in Japanese Formula 3000 championship with Nakajima Planning, scoring three victories.
- 1996 -- Finished 4th in Japanese Formula Nippon championship(ex Japanese F3000)with Nakajima Planning, scoring two victories.
- 1997 -- Served as test driver for Tyrrell Formula One team. -- Scored one victory en route to finishing 6th in Japanese Formula Nippon championship with Nakajima Planning.
- 1998 -- Drove in Formula One in rookie year driving for Tyrrell. -- Finished in the top-10 twice, including ninth at Silverstone and Monza.
- 1999 -- Competed in Formula One with Arrows, scoring two top-10 finishes,including a career-best seventh at Melbourne (Australian Grand Prix).
- 2000 -- Won eight of 10 races en route to winning the Japanese Formula Nippon series title with Nakajima Planning .
- 2001 -- Finished 21st in CART point standings in rookie year driving for Walker Racing.-- Finished in the top-10 three times, including a career-best fourth at Houston.
- 2002 -- Finished 15th in CART point standings with Walker Racing. -- Finished in the top-10 seven times, including tying career-best finish with a fourth place at Chicago.
- 2003 -- Finished 10th in IRL IndyCar Series point standings in rookie year driving for Mo Nunn Racing. -- Scored nine top-10 finishes, including a season-best third in June at Texas. -- Started seventh and finished fifth in first Indianapolis 500, the highest-finishing rookie. Voted Bank One Rookie of the Year.
- 2004 -- Competed in IRL with Mo Nunn Racing.
- 2005 -- Competed in Formula Nippon as owner-driver of Takagi Planning with CERUMO.