This englishman got his start younger than most drivers when he raced his first karts at the age of four. Competing in karts until 18, Dan moved into the Britsih Formula Vauxhall series where he came in second with 3 wins and 7 top-three finishes. The next couple of years saw him compete in the British Formula Ford circuit where he earned 7 wins and 7 top-three finishes.

In 1999 Dan moved to the US where he made an immediate impact in the F2000 series with 6 wins, and 5 top-three finishes to take the championship along with the Rookie of the Year award. Moving into the Toyota Atlantic series for 2000, Dan won his first race and another to finish second overall and taking another Rookie of the Year honor in the process. In 2001 Dan continued his winning ways by finishing second in the Indy Lights series with 2 wins and yet another Rookie of the Year award.

2002 saw Dan run a limited schedule for the IRL where his highest finish was 10th in 2 races. Running the full schedule in 2003, Dan was the highest ranked rookie in 11th overall, following his pattern of winning yet another Rookie of the Year award. 2004 was a breakout year for Dan in the big leagues. Hot on Tony Kannan's tail, Dan posted 3 wins and 9 top-five finishes, which includes a third place finish in the Indy 500, to finally finish 2nd overall.